Creating copies of a dynamic class

I’m working on a particle emitter, and I want to be able to pass in custom sprites (one for smoke, one for fire, et cetera). They are instanced on in the library as separate classes, but I want to be able to call a function like, “ParticleEmitter.SetSprite(Smoke)”, then have it start creating instances of the smoke class.

The problem is, I don’t know how to pass in a class name as an argument or how to use it to create copies. Is there any way to do this, or would it be best if I just put all my different particles inside a MovieClip and set the frame for each one it created?

I can link examples if anyone is confused.