Yes, you can use a second hand IPF unit, but you need to buy a licence from Regal or EDS. Licence is around $400-450.
If you're only gonna just mess around until you get your aftermarket ECU, I'd just flash the ECU with a Galletto 1260 cable and those maps I sent you. A lot cheaper than the IPF.
I'd only recommend the IPF if you want safe stage tunes for the longer term.