Try searching for a thread about this in the Installer's Lounge. I haven't read it, but I think answers are there. And, heck, search this forum and the Home Theater forum, too! Then find the forum that deals with the Harmony remote and search there.
A good answer is easier with a clear question giving the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw