nudone, just gave a quick try on this one so please assume this as a beta script.
based on the direction & mouse button, the scroll wheel shrinks or stretches the window. for smoother transition, edit the .ahk & change the 'NotchMove' value (see pic).
also, i can't get 'hold both buttons' thing to work so i switched the scroll wheel to be used with either 'Control' on the keyboard or the 'Back' button on the mouse (XButton1 in AHK-speak).
briefly the hot-keys:
LMB + Scroll Wheel -> Vertical
RMB + Scroll Wheel -> Horizontal
Control + Scroll Wheel -> Incremental
XButton1 + Scroll Wheel -> Incremental