Hi Bruno,
Like Tarin said, note (including the subtle stuff).
It's not really about some secret formula at this point, or some arcane mind motion, or some exotic experience, or anything of that sort.
You want to pay close attention to what is going on here, right now - anything going on is what is going on here. I think Tarin mentioned somewhere how he even made that into some kind of mantra - "what is going on here?".
Getting into and staying in 4th Jhana for some time can give you more power to do that kind of paying attention.
The distinction between samatha and vipassana gets increasingly artificial in 4th jhana, in my opinion.
Have you listened to the "Doing it vs. getting it done" discussion, available for download at Daniel's site? There is a lot of good material in there to satisfy the geeky intellectual technique-oriented angle. On the cusion (or walking, ...) however, it's all about paying attention to what is going on here - especially the subtle shades of that.
Noting practice can be really good here - it's what got me through equanimity. Or maybe the technique of "centered prayer" works for you (basically, you consent to the presence and actions of the sensate universe in your current experience, and express that consent with some kind of symbol, anything, really, a word or visualized shape for example).
Duncan Barford has a good essay on this attitude called
The Gesture. One key phrase I found particularly useful was "our perception of the rose is a part of the rose, not a part of or a picture in our mind".
Looks like I've written another long post - don't be confused by the volume of what I wrote. It's really as simple as Tarin puts it.
Cheers,
Florian