Have a look at the point entity game_team_master
To use it as an alien master set it up like this:
-name: alien
-team index: 2
To use it as a marine master set it up like this:
-name: marine
-team index: 1
team index 0 is the readyroom team, can be used for RR triggers for example (get creative

)
Anyway now you can use lets say a trigger_hurt and set it's master as one of the game_team_masters above --> for example if you set "marine" as master it will only hurt marines. The same goes for teleporters, buttons, doors etc... I use it for the alien lockable resnodes in my map and the teleporter (along with an elaborate entity mix to make the resnodes work ofcourse)
I do have to add to this that I have not tested it with trigger_hurt or the teleport area brush, I don't see why it shouldn't work though...
Just a little side note...
Are you having trouble finding the
Mapping Help and Troubleshooting sub forum?