Roku Device Registration And Linking

I'm new to developing for Roku players and BrightScript. I've been reading through the SDK and forums to try and learn how to register and link a Roku player for a fee based channel or in-channel purchases. The SDK explains a very simple set of request and responses for pre-registration and device linking.

However I haven't been able to find an example of the server side code to process the pre-reg and linking functionality, creating regCodes, etc. And of course, how does your channel know it has been registered the next time it executes.

Thanks in advance!