If you go to http://www.nissantech-info.com and register for a 1 day subscription (+/- $20), you can then view (and save) the factory service manual. If your X is too old for the system, just get the oldest one in there, as they didn't change a whole lot on the D22 chassis.

I've only got 55k on my Frontier, so I haven't changed the belt on mine, yet. I've done a lot of other things to my truck, though... So if you need an extra hand, shoot me a PM. Looks like you'd be about 20 minutes away...