>Is it possible to use the bluetooth module with an empeg through Pcat's tuner kit ?
Probably. Should only be switchable to at leat 1200 Bauds or so, but I couldn't imagine to be fast enough to transfer audio.

>Is it possible to use the tuner's PIC for multiplexing the data over the serial line ?
Why multiplexing? If this works with the spare pins, you have a normal serial line.

Well, obviously there are other "dreamers" like me, thank you, I'm sure we will find a solution.