Hello all,
Even if you are in connection (and if time allows) you can (and should) still present yourself at the check-in area in Terminal 2E (public zone).
I have flown YUL-CDG-PEK and IAD-CDG-NRT in P and both times we presented ourselves at the Premiere check-in area in 2E, saying that we were already checked-in. We were graciously and immediately escorted via security to the Premiere lounge.
While there are still impovements to be had (a newer more permanent First Class lounge is being done behind those walls across from the entrance), it is a nice service and a step in the right direction.