Actually, in this case you don't need to make an addon at all! Simply place some Spetznatz on the map, and then group them to a western unit. In the init field of the west unit, write "deletevehicle this". When you start the game, the spetznatz will be on the west side.
Another way to do it is to edit the mission.sqm file. Search the FAQ if you want to know how to do this. However, the first method works just as well as the sqm method (except in maybe one specific case), and is a lot easier.
I hope that gets it!