Changing a macroscript button?

Hey guys, I would like to have a script start up with max, which changes a button associated with a macroscript that I made, but that the user added to the interface. This macroscript should then send a message back to the startup-script to perform a command.

The idea is that every time you move a camera, the script should register this, and make a button on the UI red, so the user can see "Uh oh, I moved the camera again". Then when pressing the button, the camera movement is "undone", which you can do as many times as you moved the camera, so it works like a separate undo-history.

Problem is, I don't quite get how, or if, you can do these icon changes, or send info between the scripts. Any suggestions or guidelines?

Anything will be appreciated :)