Please have a look at this:
I am writing a script wich changes selected verts.
Lets say the user is in Box-select-mode (...or whatever tool), selects something, does some constrained transformation (example: Move in Z)
Now my script is changing the vertex selection. At this point I want to reinvoke the constrained transformation (example: Move in Z). The goal is, that the user doesn't have to hit G - Z (example) again but, the geometry sticks to the mouse and moves in Z until mouseclick.
What would be an efficient way to achieve this?