Well, it all sort of depends on how accurate you want to be, how much money you're willing to spend, and how much cutting you want to do. I've been collecting information on this build for a while, and Ben Wicker has one going (or not as the case may be) right now. Anyway, here's a basic list of what you'll need for the build:
AMT Kenworth W925 - frame, engine, hood, sleeper, cab seats (there is a small cavet to the engine)
Revell of Germany W900 or T900 - cab & interior (actual truck had a quilted rear cab panel, and you'll need to rework the rear of the cab to make the rear panel & window)
P&P Resin Works or Melbourne Model Truck Accessories - tandem torsion bar rear suspension (unless your AMT kit has one)
Model Truckin' - decals
Engine cavet - one of the trucks in the movie had a Caterpiller 1693 engine, while the other had a Cummins. As far as I know, the Caterpiller 1693 does not exist in resin.
Good luck on your project, and I'm looking forward to pictures.