i have been doing a lot of research on control net lately. I have a project dealing with it. You do have to take it down to add anything. It makes you go into program mode when you go into rsnetworx. check out http://literature.rockwellautomation.com/idc/groups/literature/documents/um/cnet-um001_-en-p.pdf
I have been reading this all morning. Also look on youtube there is some stuff there.