In light of what IdahoMtnSpyder said above, your best bet might be to get a Bluetooth headset (or a pair of them if you ride duel) especially since you already have the Bluetooth transmitting dongle in your front trunk. The dongle you have is the
Sena SM10. You can get a user manual for it
here. If you think, for some reason, that it is not connected, you can test that out by temporarily pairing it to a BT speaker that you may have, or can borrow.
The headset I would recommend is the
Sena 10S, which is a very good one with good music reproduction capability, and one of Sena's latest models. There are other Sena headsets, including the recently discontinued SMH10, which you can probably find very inexpensively now on the Internet.
You said you already had the MP3 cable in your trunk. If you also want the iPod one, you can pick that up from your dealer. As mentioned in the last post, that is nice because you can fully control an iPod with the Multi-Function controls next to the left handgrip. (Both audio adaptor cables originally came with the RT.)
The bike originally came with a detailed user guide for the Entertainment and Command Center. Much more information is there than there is in the Spyder User Manual. It was printed on a single long sheet of paper. Sorry I cannot find one on the internet for a link, but perhaps you can also ask your dealer about that.
Hope this helps you some.