Hi!
Unfortunately, Outcast does not support the mouse wheel by itself. As I like to be able to use the mouse wheel for zooming with the EVD and choosing weapons, I created a small AutoHotkey.
It maps WheelUp/Down to Kp9/Kp3 (by default this is next/previous weapon) and WheelLeft/Right to Home/End (zooming). To use it, copy it in the Outcast directory and execute it; a recent AutoHotkey version is needed
Caveats: It does not work with Win98 compatibility mode (probably as WheelLeft/Right are not supported there). There are small pauses between zooming steps, due to the fact that the Wheel can only register KEY DOWN and no KEY UP events.

Ah, good thinking. I ment to use the additional mouse buttons and the mouse wheel, but didn't want to remap the keys manually in the mouse driver software. I didn't think about using AutoHotkey, though, which makes this very comfortable.
I prefer to have zooming on the 4th and 5th mouse buttons, as that's more precise, but I think using the mouse wheel for zooming the map should work well.
So, while I'm not actually using your script, thank you for the idea :)
[edit]
Strangely, if I use AutoHotkey to for example send the key "M" (changing map size) when I press the middle mouse button, the walking animation in the game seems to "stutter" for a short time, whenever I press this or any other mouse button, which I remapped with AutoHotkey.

^^^^^^^^^^^^^
Didn't see the above poster in the search results which is why I thought no one said thanks.

Why no one thought to thank you for this amazing gift is beyond me!

Thank you for this, as I'm a slave to the mouse-wheel myself!