Contextual Menu "Save Image As..." approach

I’m creating code for a right-click contextual menu for images in a Flash movie. I’ve got no problem making the menu itself. Where I’m stuck is working out the code for a “Save Image As…” option.

I can call up the individual images in a new browser window (using getURL), and yes, the user can then right-click to save as. But I’d like to cut out this step, and make it happen right from the Flash movie.

Could anyone point me in the right direction? Thanks in advance!