
Check the station's master sync generator.  You'll probably find that
it already has horizontal and vertical drive outputs that just aren't
being used.  A couple of cables and you're in business.

Another possibility is to find a genlockable sync generator with HD and VD
outputs - genlock it to station sync, and then feed HD and VD to the
cameras.

If neither of these is possible, then you'll have to build a sync
separator.  Look at the circuit diagrams of your existing sync generators -
they probably all include circuitry that does what you want.