I alluded to this issue a long time ago when I posted asking how to get the right macro for holding a key down.  I figured out this is essentially a bug in the macro software for the mouse.

Description: if you setup a macro to simulate a key press (say '3') and bind it to a mouse button (any of them) and then proceed to use that in your game, the action performed is a KEY DOWN AND a KEY UP.  So, if you press and hold to mouse button hoping you will simulate pressing and holding the 3 key on your keyboard you're out of luck.