You basically use a loop within the camera script, with a condition for when you want the loop to stop. For example:
? showt72: goto "NEXT"
_camera camSetTarget a101
_camera camSetRelPos [-1.27,+7,+1.6]
_camera camsetFOV 1.300
_camera camCommit 0
'showt72' is the variable that cancels the loop. This example was taken from one of my missions. 'Showt72' was made true when the planes reached a certain point on the map (when they entered a trigger).
The example above basically keeps the camera at a certain point in relation to a vehicle (see the command: CamSetRelPos in the COMREF).
There are a few scripts out there (see editors depot) that do the same job. I only needed a small loop for only a short amount of time and this seemed to be the most efficient method.
Hope this helps