Frankly I can't remember: I have a feeling I discovered camera.sqs at about the time I did this, so I'm not sure. It is true that GLs can be very useful in setting up camera shots, but the great thing about camera.sqs is that you tend not to need things like that very much - the camera has an absolute position in the game world, recorded automatically.
IMHO overview pics are THE hardest thing in the whole of OFP editing, with the only exception of genuinely advanced scripting. They are by far the hardest thing in creating a good basic mission. Having said that, I managed it which means that anybody can, with a little persistance.