Time to get your rotoscoping head on - you will have to :
1. Draw a mask around your body on each frame (try to use only one mask per
frame if you can), then stroke the masks (try a 3 point thickness) and
finally hide the actual footage so you are left with an outline of you
walking
2. Export as a high quality BMP seq so you can 'trace bitmaps' in Flash
I'm sure someone else will have an alternative solution but this works for
me!
You can also wait for AE 6 and its very cool auto trace mask to path feature.
You can turn any alpha channel into a vector path (and then stroke the path with the Fill & Stroke filter.
So all you'd have to do is film yourself on a bluescreen and extract a matte.
You could also do it by backlighting yourself, blow out the background exposure in the camera to white. Bring the clip into AE 6, use levels to make your body totally black and the background totall white. Then use the autotrace function.