Satellite Radio Revisited

Alright, so I think it's really cool to have Sirius radio displayed right on the touchscreen, however the cost of install and inability to remove for home use make it inpractical, in my view. It also doesn't seem to have any of the "replay" features, which I think are good to have.

Anyway, my plan was to buy a Sportster Replay at like a Best Buy and have them do the install, DIRECTLY connecting the unit, and hiding antenna wires. Problem is, how to directly connect it. I've read a few different threads here about SLU and SLI units. I have a 2005 Prius with the AI package. So I have the JBL disk changer, but not the navigation system. If all I want is to add an Aux 1/4in or RCA audio stereo input that's selectable on the built in unit, what hardware do I need? And if I buy hardware from one of these sites, do you think I'll have a problem having the install guys at Best Buy plug it in?

Conversly, is it worth even speaking to my dealer (who by the way, completely sucked while I was buying the car from them) about installing such an audio input before I take the car to Best Buy?

Any help would be greatly appreciated.