10.6 dual boot?

I just got a new 27" Imac running 10.10.1 and I need to make a bootable partition to run 10.6 for some older software and I am having some trouble.

I have 1-10.6.6 disc 1-10.6.4 disc and 1-10.5.6 install disc that came with older Imacs that we have, but I cant seem to boot from any of them. I have made the new partition, I just cant seem to get booted up on an install disc. The 10.5.6 crashes my machine and both the 10.6 disc just go to the grey screen an freeze.

Couple thought that I have had

Do I need to buy a retail copy of 10.6 to do this? it's only $20

I do have a working 10.6 partition on another Imac, is there an easy way to move that partition to the new imac?

Any help would be appreciated.

Thanks

Mark