If you decide to keep or go with the cat5 (which I would recommend for 65' run vs. wireless)you simply put one of the female 3.5mm keystones at each end of the cable. Then you use a 3.5mm male to male cable to connect between the IR repeater and the keystone.
will the cat5 be better on signal transfer than the 3.5mm?
I am only using a keystone plate in the TV room (are they standard size holes?). The other end terminates in my "electronics closet" and would simply drop from a hole in the ceiling - no plate used there.
You just need some (preferably) solder type 3.5mm connectors with the gender needed in your situation. They have these at Radio Shack as well. Just pick two colors out of the four in a CAT5 cable. Call one color + and the other -. You may ignore the other cables. Match the colors to the same part of the connectors on both ends. You now have a custom 3.5mm extension cable.