Sorry jboy… Ive SOLVED this one.
You just need to use xboxdrv as a daemon to emulate a keyboard for OSMC as you will find via a google search. then alter the retropie.sh script to stop the daemon, copy a new config file that supports retropie (as seen on this forum) and restart the daemon.
It really is simple one you have the two configs sorted.
Im happy to post my scripts but they are “hacked” and not quite as dynamic as they should be.