Why not just connect it to a battery tender instead of removing it and then having to worry about reprogramming your radio, etc? This is the route I would go. The single charging units are fairly inexpensive, $50, and give you ease of mind that you aren't wasting a perfectly good battery.
Battery Tenders here:
Mini Cooper, Cooper S, and Clubman (R55/R56/R57) - Miscellaneous - Page 11
Also, since you're storing your MINI (assuming in a garage) might also want to check out our GarageGaurd here:
http://www.pelicanparts.com/catalog/coverking/coverking_garageguard.htm. Let me know if you have any questions.