I know this is an old thread, but I want to post to it anyway. I searched the nets for the answer to this, and finally was able to do it. I want to post here how I did it, so others can do the same...
I have a Connect Hub, but I bet this would work for any of the logitech systems because they all seem to use the same emitters.
It is pretty simple, Logitech does in fact use the same signaling as Xantech, so I bought a 2.5mm MONO cable (I couldn't get a stereo to work no matter how I wired it), cut the cable and spliced the wires inside. In mine, it was red (tip, or front), black (ring or back). I connected red (tip) to the IR, and black (ring) to ground connections of an Xantech input of a connecting block. This worked perfectly.
I used:[Link: amazon.com]
(cut the cable in 2 so I could use it for both my hubs.)[Link: amazon.com]
(but anything should work, this is just what I had handy, but keep in mind you will need the power supply, and obviously emmiters.)