parameters on subclass of movieclip

I have an Actionscript class which extends MovieClip with a few functions and properties. I can set the class of any movieclip to this class and get the functions without problem, but how do I set the properties without writing actionscript on the instance itself?

I'm building this as a way to encapsulate the actionscript and make it easy for non-coding artists to create this functionality without having to do too much actionscript.

Ideally, I'd be able to set the properties in the properties or parameters tabs. There's going to be more than one movieclip of this type, with completely different graphics on them, so as far as I know, a component won't work. I'd be okay with creating a jsapi tool to set the properties, but that seems like overkill.
Can a behavior-only component be attached to a movieclip instance and 1) change the class of that movieclip and 2)set properties on that movieclip based on the parameters panel?

Or is there another way to approach this problem?