Hmm … I’m not sure what the other tutorials can’t do for you. Could you be more specific, regarding what they cover and what they don’t?
I’d scan the sig, then draw an open mask with the pen tool over the signature, then apply render>stroke to the layer, using “all strokes” and “reveal original”.
However, if you try to export an SWF from that, and select “rasterize” for unsupported effects, you’ll get a rasterized SWF which will not be as small as a vector SWF. You can try applying something like Optimaze to get the file size down. Unfortunately however, AE’s stroke & paint effects have to be rasterized.
If you need teeny vector files, I recommend you try the effect in Flash. I haven’t tried it, but you might be able to tween a line in a mask layer over the signature layer to reveal the sig.
Hope that helps,
Steve