Custom playback control

I'd like to make my own playback control since built-in ones doesn't have captions in my language.
I have figured out that there are 2 kind of playback controls bars...
- one is stored in swf files,
- second one uses BMP graphics.
I'd like to modify playback control which is stored in swf files. Can someone give me a hint or two about this?
Or is it better to make one from scratch? I guess this have to be done in Flash...

Thanks,
Daniel