Not quite the same thing, I know, but what you could do is use a secondary IR reciever (a bit like we've got in our Honda AV car to control the DVD in the boot) that picks up the IR signal, transmits it over an RF link, then retransmits it as IR at the remote end. You could then mount an IR pickup somewhere in the dash, and use the original Empeg (?! ;-) remote to control the unit. IIRC, the whole kit doesn't cost too much, and seems to work OK in the Honda.
Cambridge Car Audio