I have never tried this "in car" ... is it possible to replace the idler pulley and the tensoner pulley/arm with the engine in the car? My engine is "noisy" and it's coming from the FEAD.

Yes, i took out both before i pulled my engine. Used a stubby torx bit on the tensioner with adjustable wrench to break it freee and i believe an offset boxed end wrench on the idler.

Yeah, it's a PITA but not that bad. I think you will definitely need 2 people though.

Thanks guys ... I'm kicking myself for not doing this before dropping in the engine a few months back (3L).

It is definitely possible with a short torx bit like previously stated. I just did it this past weekend and that�s exactly what it took for me. I didn't even need to raise the engine at all. I just slowly worked at it and managed to do it by myself. I found the bit at AutoZone btw. It was sold in a kit with other torx bits though. Good luck.