Clueless Sirius Installers?

I've talked to several Directed Electronics authorized retailer audio installers in the SF Bay Area and have been pretty disappointed with their level of knowledge about installing a Sirius radio so I can operate it from the touch screen. One shop said it was impossible to hook up Sirius to the factory radio, even when I told him my 2008 Prius has navigation and is satellite capable! And remember, he's an authorized DE dealer!

I called another shop and told him the parts I wanted to install (SC-C1 universal receiver and TOY-SC1 Interface). Even though he too was a Directed Electronics authorized retailer, he said he'd have to research it and get back to me.

Finally, another shop was somewhat more up to speed, but they wanted to install the antenna on the dash. Is that a good option? I'd rather have it in the rear spoiler, but maybe I'm just being fussy.

Can anyone recommend a good shop in the SF Bay area (preferably near Oakland or Palo Alto)? I really don't want to hire someone who'll be doing this for the first time. Another option would be to do it myself, but that would probably turn out very badly!

Thanks