You can't. The pgp only starts commands, any further user input needs
to be done on the command line or in a macro.
You can have a macro under a button or on your right click menus.
eg when I want to join a load of lines and make a polyline out of them,
I right click and hit 3 (just my set up). The line on the shortcut menu
looks like this '3joinall' and behind it is the macro to do the job.