how do i wind my odometer back? (xb = cable)

[xbandrew]

i put this the xseriesfordclub section but then realised id probably get more answers and people looking at it in this section.

ok now everyone who has read that thinks something dodgy is going on. but that is not the case, i have got an xb (lets call it xb1) that has miles for speedo and odometer, and have got another xb(parts car), that has got km for speedo and odometer, basically what i am going to do is swop em over. but i have a reading on the km odometer of 252857 and need it to be 141680.5km (because xb1 has done 88036miles). so i need to know the easiest way to wind it back, rather not do it by hand, have tried a small batery powered motor but keeps losing grip and is still slow, is there any quicker way?

thanx