IR-LED on remote: if you have a video camera, most are sensitive to IR. Check it first with a known working remote, ie TV, other stereo etc and check if you see the LED light up when pressing buttons. If you do, then check the empeg remote.
I think you can get a little card/film type thing that has a material that gets excited by the IR light, and emits visible light instead. Don't know where one would find it, Radio Shack maybe?

IR sensor: Install Hijack and go to the Button Code Display page and then try any and all remote you can get your hand on. If the (carrier) frequency the remote uses is the same as the empegs you'll probably get codes displayed on the page as you press buttons. Sort of hit and miss though, since you can't be sure the remote is 'understood' by the empeg IR sensor. If you have or can borrow a Kenwood car stereo remote, it should work though (unless you deselected it in emplode) as that's what was originally used by the empeg.

/Michael