I hate to be blunt here, but if you don't know how to set kext permissions maybe you shouldn't be working with a 4650. You are going to have do do a lot of testing and working with the CLI to find the right combinations of kexts and boot loaders that will let you get this working. Working with this card is not for people who do not know how to use and work with the CLI.

Your only other option is to find someone still running 10.6.3 who is running with the same boot loader you are using and get that person to send you his kexts. Of course without knowing how to set kext permissions that isn't going to do you any good.