Yes its not a problem doing a MCL2 setup with what you got.
I sugest since you are a goldmember to go to mainsite under catalogs/service manuals link and download the system manual 89-90 which will cover all you need to know.
For audio you will need a MCL2A in each room with a tranciver like the MCL2047 type which the latest.
For ekstra tv's you will need the MCL2AV tvkit in the linkroom. The Tv takes the space of the tranciver.
The setup would look like something like this:
Local room: BC9500 with AUX going to the AUX of the MX5500.
Linkrooms audio: MCL2A with tranciver goes via mcl cabel to speaker pair 2 on the BC9500 or next linkroom.
Linkroom TV: MCL2AV tvkit connects to second MX via AUX. AV panel goes to the mcl cabel and then to speakerpair 2 on BC9500. RF cabel goes to local room for video signal after the distrubtion point.
Note: You can only have 4 MCLA units in total unless you use the mcl expander.
That's the basic setup. Yes the MX can be used as link device. In a linkroom you don't need a tranciver but you will have the option and you will need the AV tvkit.