Check out the thread nearby about the 1999 Dodge Durango. It has details of a product called the OEM-1 which allows you to connect the empeg directly to the factory radio (and I think Bose is one of the supported ones).

This is also in the FAQ, by the way. Please give that a scan.

(edit: I just updated the FAQ entry to make the link to the OEM-1 more obvious and to show Tod's durango as an example).