The main 5 channels cannot be reconfigured outside what is essentially Zone 1. The 6th and 7th channels can be directly configurable to power a zone 2; zone 3 is just an rca output pair, need to connect an external amp.
The only other way to use it in another "zone" is to use the main preamp outputs to send channels to another room, but even then, it's not a second zone, just repeating the signal being played over the receiver's zone 1.
I wish it was configurable the way you are wanting it; as I'm currently only using my 3806's internal amps to power my surround channels since I'm using 3 power amps connected to the preamp outs to power the fronts.