1) So, there is a new IR over COAX system installed, and he has an existing hardwired IR system?

2) If you mean RF as in an RF remote control, then no you cannot distribute these signals via a IR system.

3) If it indeed is a Xtralink system from Xantech (IR piggy backed upon the coax cable) then you simply need to use a coupler to pull off that IR signal and insert it into the receiver input on the connecting block. I believe this will work....use signal and ground for the connection.

There is another thread here somewhere where we have discussed the Xtralink system and how to properly wire your distribution for enhanced operation. You must be careful of grounding out the IR signals on the coax by a TV that does not have a Xtralink recevier system attatched to it.