Sorry to dredge this back up, but I only came across this thread today while searching for something else.
Here are some pics showing one way to mount a York on the driver's side of a 4.0 Liter in an XJ.
Credit for fabricating the mount goes to Scott Isferding at Diamond Off Road in Haslet, TX. Scott's the best.
This location is ideal for my setup; it left plenty of room for a small manifold, pop-off valve, and pressure switch on the outboard side of the compressor. And of course, it left the factory A/C and battery location completely unaffected. The only thing sacrificed was the stock breather box (no great loss).
This setup was installed in late 2005 and has worked well since.
The belt is a Gates K061130.