[MacDV] How to Trace Route on Map in FCP HD?

[Tony Fincham]

I have scanned a map as a still clip into a FCP 4.5 project, and want  
to insert the drawing of a red line across the map (as if by hand) as  
the clip runs in the time line to show a route being  drawn across  
the map.

How can I do that please in the simplest way? Is there more than one  
way? At the moment it is defeating me on how one can to do it. Can I  
do it within FCP, or does it need an external program? I have Photoshop.

Tony