It's not exposed in the customize UI menu as far as I know. What you end up doing is creating a simple macroscript and bind that to a key. First you turn on the listener, then you toggle preserveUV on/off to see what the commands are then you include those commands in a "if then else" statement and wrap it all in a macro…
Mark Dygert and kraemology, you guys rock! I use as many hotkeys as possible and the script is way helpful. BTW if it matters to anyone I found this thread by googling 3ds max preserve UVs script I just registered here, it was long time coming. Cheers all