G'day John,
The simplest thing I can do is recommend that you look at my QR RM55 rail motor set. The trailer car is a good example.. It's on the DLS, <kuid:329364:1262>
I made the doors for each side a separate mesh with its own animation. So they are not part of the default mesh.
The names for the mesh-table containers are the key to making it work.
Also, if I remember correctly, I just copied all this from the BR MK1 SK built-in. It's included in TS2010, <kuid:-3:10074>
Have fun with it.. and keep up the great work you are doing with content.