I did this a couple weeks ago. It was much easier than I thought. I'm assuming the E92 M3 knob is the same as the M5 knob that I used.
My E90's iDrive knob was a single piece of metal, hence, that wasn't a suitable donor. Thus, I ordered a regular E92 knob from Tischer, then popped out the metal guts. (The four prong connector.) With that popped out, the M5 iDrive knob actually PRESSURE FITTED on to the metal base that I removed from the E92 knob. In other words, no adhesive needed.
It's been a few weeks now, and no problem with the M5 knob coming off despite there being no adhesive.
Overall it's a pretty easy mod. The difficulty is tracking down the actual M iDrive knob. I got mine on eBay.