Finding a simple way to strock object's edge ? Strock animtion like curve's bevel ?

Artistic Support Animation and Rigging
1

I have a object, I want to make a animation – strocking the object’s edge.
I hope it seems like writing or drawing the object’s edge.
Is there has a simple way to achieve it？

edit: I hope the strock animtion like curve’s bevel object, can set start or end becel factor…

2

Using Game Engine is quick:

https://vimeo.com/23562207

3

Can you tell me how to do it? Thanks!

4

I found a way:
Cube => Edit mode => Delete only faces => Object mode =>Alt C => Curve from Mesh/Text
So can choice bevel object and insert the keyframe in Strat/End Bevel Factor make animation.
but there is another problem: the animation will start at 4 vertices in the same time, not one by one.
maybe must sepaate them became new curve object ? can I sort vertices in curve?