I did it ! I'm S-off. It helped to have the audio file that clicks every 1.75s. The good news is that I got back my system en toto ! (CleanROM 1.7.5 + Incredikernel Beta 3-1).
So I can load new ROMs more easily supposedly. I'd like to try the latest ICS leak. Guess I'll go find those instructions. Let the fun begin !