FYI, guys. Just wrote this up...
If you have a relatively recent Leica lens but it's not coded... You can either temporarily code it with a black marker - or permanently with a properly machined mount flange. The problem is, this procedure can be expensive and lay up your lens for many weeks.
Follow along with this illustrated HOW-TO to convert your lens using a third-party mount flange. $15 and 15 minutes is all it takes.
Converting to a Coded M Lens Mount