This link tells you where to get a cable. That is the first step.
Shawnsheridan will link you to the software download. He is also on Bimmerpost with same name if you don't want to open a new account.
2013 ///M5 Individual
Monte Carlo Blue, Platinum Full Individual Merino, Platinum Alcantara, Piano Black, Exec Pkg, Drivers assistance pkg, Bang and Olufsen, 20" wheels
Eisenmann Sport Exhaust, Bel STiR+, Laser Interceptor QUAD HP, Zaon MRX