it also depends how stock the car is.. ie if you have all of the emissions equipment, stock fan and fan shroud etc, then it's quite a pain just to get to it.
removing the crank pulley bolt is generally the most difficult part of it all, having impact wrenches handy is definitely a good thing to have for removing it. you'll also want some sort of puller to remove the crank pulley, and crank timing sprocket. (i used block of wood and hammer, but i was lucky and my pulley was not stuck on there very good)
make sure you replace every seal you can when you're there (front crank seal, both cam seals, water pump etc) as well as the woodruf key(or keys depending on your year)
a good Complete list of parts you should replace can be found here:
http://z31.com/wiki/doku.php?id=parts_list:timingbelt
definitely make sure you replace the CHTS and its subharness when you're in there, cause it's a royal pain to try and replace that with everything assembled. test the chts before you install it if possible to eliminate any possibility of installing a faulty sensor.