subscribing a system to a config channel or system group using the RHN API

Issue

• I am needing a way to subscribe a system to configuration channels and system groups. I do NOT want to use activation keys based on the fact that if I used activation keys for everything, I would end up with an enormous amount of activation keys and I do not want to manage that.

1. How do you subscribe a client to a config channel via command line and set its rank/priority?
2. How do you subscribe a client to a system group via command line?
3. If there aren't any commands/packages to do this, is there possibly an internal python script that does this? My assumption is that this will need to be done via python script.