Don't want to test the hardware

I am trying to build a Snow Leopard image that will boot all current Macs. Apple made this much more difficult by recently releasing updates specific to only the new iMac and Mac Mini. I thought I could just build two new images with those specific updates until 10.6.5 is released and everything is updated again. When I try to install a update it tests the hardware and tells me I can't install this update on this hardware, I build all my images on the newest Mac Pro I have.

The question is how do you modify the package installer so it doesn't read the hardware on install. I see on the web where people mention that they have done it but not how they did it. Any help would be much appreciated.