I never installed it with a retail cd but that also should be no problem because the concept is the same.
Use the nawcom mod cd and start with it and follow instructions.
After booting you have to run the Disk Utility and create a GUID partition.

Here is a instruction to install it: http://prasys.info/2010/10/nawcoms-b...-to-empireefi/

Write if there is any problem and i will try to help you.

For 10.6.4 you have to use legacy_kernel 10.4 and so on....

And best thing is if you don´t select kexts if you where sure that they will work.
I would just select a bootloader for example Cameleon 2 RC5 and the kernel.
We will install other kexts for your other hardware after getting into the OS.
It is improbable that your hardware works just by installing the OS.

What for a Graphics Card do you use because we have to think about it how to get it working?!