Ideas Welcome, Low Level Mouse Events

My current project is related to Accessibility. Certain parts of the accessibility modules will help me and are being tested.

One requested idea is to make use of a 5 button mouse. By default the 5 button mouse works per the defaults: Thumb1 does a Back, and Thumb2 does a Forward.

The special need that we have is to eliminate the need to use the keyboard in combination with the Left mouse button. I'm trying to map it like this:

Thumb1 = Hold_Shift_L + Regular_Left_Mouse_Button + Release_Shift_L
Thumb2 = Hold_Control_L + Regular_Left_Mouse_Button + Release_Control_L

This would let them make non-continuous selections and shifted selections without the keyboard. It seems like imwheel is the closest software package for this purpose, but it seems incapable of sending a physical mouse click after another mouse click. Can anyone confirm this is true?

What I tried in the .imwheelrc file is this:

".*"
#,Thumb1,H|E|L|L|O
,Thumb1, Shift_L|Left|-Shift_L


The commented line works great, click Thumb1 and the string appears in the current window. You also can issue a Control-A to select all, works great. But when you attempt to simulate a mouse click, it doesn't seem to understand how to do that. The line below the commented line above to me should work, but doesn't work. I also tried Button8 instead of Left and that also does not work.

Anyone know of another program or technique that could provide this functionality?

Thanks!