Strongt is right. I wired in my XM radio, GTech, and radar detector all in with the radio and have never had a problem. If you mount the XM receiver on your dash, there is plenty of room under the matte black plastic dash piece for the power box as well. I just ran the power wires through the dash on the right side of the car where the speaker wires go down into the dash, over to the radio hole in the dash.
Yea the pink wire is just a constant 12V+ source, like hooking it straight up to the battery, this one never turns off unless it blows the fuse. The red and white wire is the 12V + that turns on and off with the keys acc position.
The stereo wire is the EASIEST to get to. If you wanna tap into another power source you can use the cigarette lighter or go directly into the fuse box but i dont see why you wouldnt just go with the easiest route.