Using ISA Server with Starband / BT Openworld 2-way (Gilat-based) Satellite Connection

I’ve noticed a number of posts in forums about how to set up ISA Server to work with a Starband (and other Gilat based 2 way satellite internet connection). I thought that as I am using the connection it was time to set up ISA Server on the gateway PC running the Starband software and see whether it could be made to work.