Paul,
If I hear you correctly, you have a Jensen receiver and the factory Clarion changer and wired remote, right? They won't work with anything besides a Clarion C-bus receiver or the remote will sometimes work with CeNet receiver. See other posts. As far as removing the wood trim panel/frame, you have to access the angle brackets holding it in place. Easiest to do by first removing the radio (which you've tried) then you can get to the angle brackets holding the changer. I have had to use a flat head screwdriver in a pinch but it will trash the radio.
If I was to bet, all you need to do is find a used Clarion C-bus radio and your remote and changer will probably work just fine...
Dan