I had these problems with my Dell lappy that I was installing on.
I must have tried an install at least 10 times and never could get the keyboard and trackpad to work despite the addition of some kext files.

Then I found: http://osx86.sojugarden.com/

His installer works perfectlly. I follwed the instructions to the letter and I have a working install now with working keyboard, trackpad and graphics acceleration working.
I also did an update from 10.6 to 10.6.3 (as I have a retail copy of SL) and it all works perfectlly including my wireless.

The good thing about this installer is it does show you how to do it properly and it is using a retail CD, not some distibution, so the install is pretty clean and more legal.

Personally I used my broken installation to setup my USB key using his installer and then reinstalled.

So, don't get a loan, just get the installer and £25 for a Snow Leopard CD.

!m!