Yep, Felix is on it..
Basically you open up the Part Code list with Notepad. This will have all your animations codes. This is what the compiler uses when it compiles your plane.
Note that you can then copy/paste/modify a part name and change it to one that you wish.
But, you must make a 'new' name and any L:var custom animations must be different (in naming) then any other part in that list, or it will mimick other parts that share the same name.
Example; (L:SunVisorLeft, bool) <-- if you have any other parts with that code in it, they will all work at the same time, so you must change it, such as 'SunVisorLeftA, SunVisorLeftB, etc..
Same for parts name tags. You cannot have two or more parts with the same name tag.
When going out to make such custom "new" animations, make periodic backup copies of your master parts list. If you mess it up, you can always backstep. Remember, one small symbol will cause the rest of the entire stack of code to not function, which means when you burn a MDL, the animations will not work until you find out what symbol you messed up.
Learning code will be another thing to do. Very difficult at first. Best to use 'similar parts' to go by and gradually learn how they work. Ask questions on code here or in Gauges to find out meanings of things. The best area to find out all the lists of commands and aircraft readouts (base codes) is in the FS2004 Panel SDK in the Docs folder. Some brilliant reading in there, and all tag and readouts are in there as well.. (Well, most of them, some exist and are found at Nick Pikes great website).
Once you start to learn how to make your own code, you will be addicted. You'll have so many wild animations going on.. Your list will double in size.
Just be careful and be patient.
Bill