Thats the setup that I have, although not installed yet.
I was wondering the same thing, and was planning on wrapping as much of the cabling in foil or some sort of shielding.
I have a "Center" speaker space on my 944 that was a single speaker solution that never had a speaker in it. The grill easily comes off and will house my USB hub with GPS BU-303, Bluetooth, 802.11G, ATI remote dongle & a card reader. The wiring will have to go directly behind the headunit ( JVC KD-LHX500 )..
I also will be changing out my broken electric antenna. When I installed the HU, I had to splice the antenna wire, so I will try to find a double shielded antenna and re-attach antenna connector on HU.