Animating random bugs

is there a way to create a path on-the-fly, and then assign it as a motion path for existing movieclips?

the idea is to create some critters which crawl across the screen at random interval and prefereably take random paths across the screen.

I guess the other alternative is to have existing paths in the library which are exported. Can these be used/assigned as motion paths?

Thanks in advance, look forward to your replies

Cheers

Ratbaggy