I'm not entirely sure what you're asking - what do you mean with "which voice can be inserted"?
Here's some commands that I thought might help you:
cg_zoomstepsniper "16" - put in this command and you will have only 2 levels of zoom when using your sniper rifle
cg_useWeapsForZoom "1" - If you set this to 1, your weapon cycle keys while change zooming in and out
Use these bindings in concution with the cvar above to use your mouse wheel for zooming:
bind MWHEELDOWN weapprev
bind MWHEELUP weapnext
That's what I was thinking about when I read your post, but I'm not sure if this is what you are looking for