Random Movement Within An Oval?

I am looking at the Kirupa code for random movement (Random movement in Flash MX), and I am trying to figure out if I can limit the movement to the shape of an oval.

I want to do an overhead shot of a bunch of little people swiming in an oval swimming pool.

Does anybody know of a way this is possible?

Thanks
Mathias[size=4][color=#003366][font=Verdana][size=4][color=#003366]

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