DanyL from PSX-Scene has released an EASY and newb friendly program to add PSGroove on iPod devices (and various others including: sansa E200v1, E200R, C200v1).
To quote: I built a small program that allows easy installation of PSGroove on iPod devices. It's still in beta and it lacks of automatic installation of iPL. But it works pretty well.
[Download RockBoxPSGroove Installer] [VIA PSXScene]
Thanks to condorstrike for the tip