Be careful if using a DIY face plate, as it will probably have a circuit board on the back to connect the cable to, these have massive signal loss and will cause you problems. If you do get one, just get one with a straight through thread connector:
http://images.productserve.com/previ...4/39965945.jpg
However best just to have the cable coming straight through the wall into the equipment (no joint, just a face plate with a hole in for the cable to go through). Then if you ever have a fault and you get a VM tech to visit, ask him to fit a wall outlet for you on top of where the existing cable comes in (might have to grease his palm a little).