I don't see any reason why it could not be re plumbed to work. The wire harness just provides a means of stop and starting the mixer from outside the loader. (and also bobcat a means of making sure it does not work on a competitor's loader)
You should be able to bypass the valve on the unit and plumb it directly through the mixer motor and control it from inside the loader. Heck If you want to you should be able to add a mechanical or electrical spool valve the would let you start, reverse and stop from outside the loader.
Can you post some pics of the current plumbing and control valve?
Ken