Yeah, just start with a 2x2x2 block and keep extending it until there are only two faces left, then fix the bad edges (there can be up to 9), build a block on R and extend it with two corner/edge pairs, and finally do whatever you feel like for last layer (I do EP CO CP, but if you know a bunch of PLLs you can always do CO EP CP or CO CP EP). Petrus is really fun on the megaminx although the recognition is even harder than on 3x3 blockbuilding methods.