Rewiring 99 tahoe windows with new switched and new relays non factory

Got a question here about some wiring. I have non of the factory wiring in the gutted 99 2wd tahoe that i just purchased. I have made up my mind to run a aftermarket 21 circuit wiring harness. It will have a 6.0 lq4 that will have a stand along wiring harness so the aftermarket harness will run everything else. I am having an issue on how to redo the wiring for the window motors to be able to use the factory switches. Anyone have any ideas?