And depending on the quality of your mouse, you might want to do something like this in you q3config.cfg:
Code:
bind KP_MINUS "ut_zoomout;sensitivity 27"
bind KP_PLUS "ut_zoomin;sensitivity 10"
Btw, 27 is my normal (usual) sensitivity, while 10 is for easier aiming in zoomed mode. Depending on your mouse/system settings these numbers might vary greatly.