A mate of mine is over this weekend from the states and I got him a bike sorted (at a cost! - £200 for the weekend on a 650GS) from Williams in MCR. You contact the WIlliams Car rental desk and they sort the bike hire from there.
Williams you say, BUGGER I have just been there to pick up my bike after it needed new gearbox and clutch Was too concerned with that to think straight!
Mind you got to go back on thursday morning so will enquire then. cheers fellas