When you do timeline tweening, it is pretty much hands off as far as interupting them goes. If you change anything about what the timeline has written in stone, you break the tween. If you use coded tweening you should not have this problem.
Yes, coding the movement/tweens certainly works. And I don't want to interrupt the tweens, all I want to do is apply a custom filter... it astounds me that this doesn't work while it works fine when I assign the available flash filters via the IDE.
Is there another way to achieve something like this? What I'm looking for is a way that a non-tech-savvy person could animate stuff in flash while the rendering of the objects could be tweaked using custom shaders. The only alternative that comes to mind is to render all symbols on stage to a bitmapdata, apply filters there and then finally compose it to a large bitmap... but that sounds really costly in terms of performance.
As I just said, when you build a tween into a timeline, it is written in stone in the file when you compile, and anything you do to change what it has memorized will break that tween. You seem to already know all of the options available to you, so you just need to pick one. Not all things are destined to be do-able by non-tech-savvy folks.