alvisdl,
Are you wiring it direct, or are you putting in an aux fuse block and relay, etc?
If you just want to wire it in directly, the switched tail light wire is in a bundle on the left side under the passenger seat. It is blue on my '06, not sure what colour it is on other years.
Separate that wire from the bundle, and tap into it either with a t-tap, or else pare away some insulation and splice your power lead into it and then solder. Re-wrap with electrical tape to keep the electrons in and the nasties out.
That should work for you... if you need more info PM me, and I'll see if I can take a few pictures and post.
You may want to consider adding an aux fuse block to control the Autocom, any other electric gear, GPS, etc... not much more effort, and well worth it IMHO.
Griff