Nissan Altima: Accessing the back of the Radio

I just purchased a Sirius Satellite Radio (Audiovox PNP3) for my 2005 Nissan
Altima 2.5. I would like to hard wire it to the back of the audio system,
and I'd like to do it myself.

Does anyone out there know how to gain access to the back of the stereo?
It's the standard, factory-installed audio system. Any help would be
appreciated. They sure don't offer any tips in the manuals that came with
the car.

Thanks,
Pete

The other solution is to by a new head unit (stereo) that has input jacks
in it.