Hi Mike
I think you mean you want to create a fictious island, Right?
I've never done this before but if you use Airport for Windows and lay a sand or gravel polygon down in the spot where you want the island it should create a flat sea level surface. Then you add another polygon ontop using the same number of "points" but assign it a 1 meter or 3'-4'-5' altitude I was told this will create above sea level land.
The key as it was explained to me was to make sure the 2nd polygon had the SAME amount of points.
Remember, I haven't tried this myself.

FaxCap