0x1b Is there a way to get the middle mouse button scroll wheel function to work?
That should work without any config with standard USB mice. But, if you're using a custom xorg.conf, then make sure it has something like this (mouse driver):
Section "InputDevice"
    Identifier  "Mouse0"
    Driver      "mouse"
    Option      "Device" "/dev/wsmouse"
    Option      "ZAxisMapping" "4 5"
EndSection
or this, with the ws driver:
Section "ServerLayout"
    Identifier  "X.org Configured"
    InputDevice "Mouse0" "CorePointer"
EndSection
Section "InputDevice"
    Identifier  "Mouse0"
    Driver      "ws"
    Option      "Device" "/dev/wsmouse"
    Option      "ZAxisMapping" "4 5"
    Option      "WAxisMapping" "6 7"
EndSection
The "WAxisMapping" is kept for 2-finger scrolling--which doesn't work yet on NetBSD on my HW (Elantech touchpad).