Does anyone know where i can get mileage adjustment tool for an e36 BMW??

i've found this place but its around £900.

www.dashmaster.com/diagnost.htm

if its just a case of a bit of software and a lead. Can someone sort me out with the pinouts (or a cicuit diagram of any boards) with a copy of the software and i'll make it WELL worth their while!

or a cheaper website would be nice!!