You could use a periodic event that goes like this:
E - every 0.5 seconds of game time
C -
A - set angle of attack of current camera to XXX over 0.6 seconds
A - set distance to target of current camera to XXX over 0.6 seconds
A - set rotation of current camera to XXX over 0.6 seconds
personally i dont think there is a way to do this, f u mean like legacies u culd move ur mouse off the unit and use the whell it jus ****ed the camera up bad and u had to use the cam commands, but if im lost then dont respond to me :P
If you remember back to the rpg made by blizzard called warchasers or comething like that, they disabled the mouse zoom. If I remember exactly they made a periodic trigger that set the angle of attack and rotation to the default. Just load up the map and take the exact trigger, or look at it and create your own.