You can do this, but it will require a Mapped Key to go along with the Repeater Region -- or you can use a Click Bar instead. I use a Click Bar with 2 buttons spread over all of the regions, one red and one blue, and they will perform different clicks (shift, ctrl, whatever) and round-robin some of them.
The trick here is to use the mouseover feature for your Repeater Region or Click Bar Button, also described as "Mapped Key on enter/exit". I use a 2-step Mapped Key, set to "pressed OR released". In step 1, I enable a Key Map that has custom bindings for various mouse clicks while my mouse is over my Vuhdo window --
Key Map State Action, Target=current window. In step 2, I disable it the same way.
Then in this Key Map that gets turned on, each Mapped Key is set up for the clicks I need. First it syncs the cursor with a
Sync Cursor Action and then sends a Keystroke with Mouse1 or whatever click combo.