I have seen lots and lots of tutorials on this, but none of them worked for me as it was never explained well. Now I did this and I am booting Ubuntu 9.10 and Mac (iAKTOS v7) fine. So I have the right and responsibility to publish this. 
Step 1:
Now the first step will be downloading the image for Mac. I used iATKOS v7 as it was the first one I found while I was searching for it. So if you don’t want to take your effort and search it, just download it from here.
Magnet URL 
magnet link)
If the above link is not working – copy This ->
magnet:?xt=urn:btih:ce66138e8e39b9f42377002d879a485d62cabd33&dn=iATKOS_v7&tr=http%3A%2F%2Fdenis.stalker.h3q.com%3A6969%2Fannounce
Step 2:
After download completes, just burn it to a disk. (The disk will be bootable)
Step 3:
Now you will have to create a primary partition and assign boot flag to the partition. But creating a primary partition will defer according to the OS you are using, but basically it all are the same.
So If you are using
Windows 7 or Windows Vista
Right click My computer and select manage. Then select disk management under Storage. Now check if you have a free primary partition already. You won’t be having it in most cases. So you are going to create it now. First make a free space around 15 GB in any of the primary partitions, and Shrink the volume with free space to get a free unallocated partition of ~15GB. Then you create a new primary partition with Quick-format option and Compression enabled. Give it a proper Label, so that you will easily recognize it while installing MAC. Now right click it and make that partition Active.
Any Linux
Install GParted. Open it. Then create a primary partition with NTFS filesystem. Make it bootable( you can find the option to make it bootable in manage flags option in the right click menu for a partition).
Step 4:
Put the iATKOS v7 DVD in your dvd drive and boot from it. Before pressing “I Agree” just read the whole thing. Its not a copyright info junk. Its the Read Me for iAtkos installation. If you need, just save it by the option given to your hard-disk. Now click I Agree. Now Open the Disk Utilities and then you will find the Mac Os Primary partition you just created from your operating system. Right Click on that and select Erase. In the erasing dialogue box, select file system as Mac extended File system. And now click on erase. After erase completes, Exit the disk utility from the utility menu which will be there on the left top corner of you monitor. Now you will be able to select the destination. Select it and click on next. Now you will see an advances/ customize button on the left bottom side of the dialogue box. Click it and you will be presented with all the drivers. Most of the systems will work with the default selection, but some does not. Here you will have to be careful. In my opinion, just select the needed drivers from network, and systems. (Only needed drivers). If you have read the I Agree part fully, you will be able to make selection without any confusion. And you may have to select the PS/2 mouse and Keyboard driver from the system drivers sub-menu, or else your keyboard and mouse may not work. Now after making customization just click ok and proceed with install. After the installation completes restart the system. Check if the Mac is working fine. If its not working you might have done something wrong with the driver selection.
By the way, be sure read the Read Me from the I Agree part. This is a must. If you messed up your system, it not my responsibility.Just take your time and read it. Or play with it some time, with all the combination of the driver sections. Now I will tell you about the Dual Boot Part.
Step 5:
This is the easiest part. Just boot into a Ubuntu 9.10 live Cd/DvD. Mount the partition with Linux installation.
Your Ubuntu partition is now mounted. You will need to use the Terminal.
Double check if your partition is correct.
mount | tail -1
You will see an output similar to this:
/dev/sda2 on /media/0d104aff-ec8c-44c8-b811-92b993823444 type ext4 (rw,nosuid,nodev,uhelper=devkit)
Use Tab Completion in Terminal to complete the path.
To make sure this is indeed the Ubuntu boot partition, run ls /media/0d104aff-ec8c-44c8-b811-92b993823444/boot, substituting 0d104aff-ec8c-44c8-b811-92b993823444 with your volume’s UUID from before, which should output something like this:
config-2.6.18-3-686 initrd.img-2.6.18-3-686.bak System.map-2.6.18-3-686
grub lost+found vmlinuz-2.6.18-3-686
initrd.img-2.6.18-3-686 memtest86+.bin
If what you have is not similar, unmount it and try another partition.
Now that everything is mounted, we just need to reinstall GRUB by specifying the correct directory and the correct drive name:
sudo grub-install --root-directory=/media/0d104aff-ec8c-44c8-b811-92b993823444 /dev/sda
If you get BIOS warnings try:
sudo grub-install --root-directory=/media/0d104aff-ec8c-44c8-b811-92b993823444 /dev/sda --recheck
Replace /dev/sda with the location you want to install GRUB on.
If all went well, you should see something like this:
Installation finished. No error reported.
This is the contents of the device map /boot/grub/device.map.
Check if this is correct or not. If any of the lines is incorrect,
fix it and re-run the script `grub-install'.
(hd0) /dev/sda
Now in terminal, just type,
sudo update-grub
If you see your Mac OS Partition label in the output, its ok. Now if you reboot , Mac will load.
But still again if Mac doesn’t load don’t panic. We have one more way to do this.
Download This File: PC_EFI_v80
Extract it, and copy the boot_v8 file to/boot, use this command to do that,
sudo cp /pc_efi_v80/boot_v8 /boot
Now again enter the command:
sudo update-grub
Now reboot the system, while shutting down, remove the live CD, and press enter.( You will be asked to do so, so do it!)
Now there will be an option to boot from MAC if you done all the Steps in this guide.
Step 6:
Boot From MAC 
Comments, feel free to ask any doubts and put any comments unless its spam. 
Use Tab Completion in Terminal to complete the path.
To make sure this is indeed the Ubuntu boot partition, run ls /media/0d104aff-ec8c-44c8-b811-92b993823444/boot, substituting 0d104aff-ec8c-44c8-b811-92b993823444 with your volume’s UUID from before, which should output something like this:
config-2.6.18-3-686 initrd.img-2.6.18-3-686.bak System.map-2.6.18-3-686
grub lost+found vmlinuz-2.6.18-3-686
initrd.img-2.6.18-3-686 memtest86+.bin
If what you have is not similar, unmount it and try another partition.
Now that everything is mounted, we just need to reinstall GRUB by specifying the correct directory and the correct drive name:
sudo grub-install --root-directory=/media/0d104aff-ec8c-44c8-b811-92b993823444 /dev/sda
If you get BIOS warnings try:
sudo grub-install --root-directory=/media/0d104aff-ec8c-44c8-b811-92b993823444 /dev/sda --recheck
Replace /dev/sda with the location you want to install GRUB on.
If all went well, you should see something like this:
Installation finished. No error reported.
This is the contents of the device map /boot/grub/device.map.
Check if this is correct or not. If any of the lines is incorrect,
fix it and re-run the script `grub-install'.
(hd0) /dev/sda
