Googling for "windows api keyboard alt key excel", this is the first
result. Looks doable, maybe not easy.
http://www.informit.com/articles/art...&seqNum=4&rl=1

Steve wrote:
I have a flowchart made up of autoshapes in XL. I have assigned OnAction
events to each shape. The user can progress thru the flowchart by clicking on
the shapes. I only want to allow the user to backup if the ALT key is held
down while clicking on a previously selected shape.

How can I recognize when the ALT key is pressed via code ?