The GM Stage pulleys fit on the GM Stage Kit hub. ZZP's Modular pulley system includes a new hub (different from GM's), and pulley(s) that fit onto that hub. If your car has a GM Stage Kit, I would go with a GM Stage pulley (unless you want to go smaller than a 2.8).
As far as the mechanic having the tools, you will probably just need to call them and ask. I had my local Saturn dealership install my GM stage 2 kit back in the day, so they obviously had the right tools.
If you plan on going to smaller pulley, you will need to get a new tune.
2004 Saturn ION Redline - She will be missed!
2012 Nissan 370Z NISMO
Former Redline Mods:
GM Stage 2, K&N Cold Air Intake, 17" Motoring Drifters, Autometer Boost Gauge, Aeroforce Interceptor
1 of 1012 Onyx Black 2004 Ion Redlines