Hello,
The UPS script you are using is a great script and indeed what you are trying to do can be done with UPS.
Lets say you want 10 enemy units to spawn at marker 'A' once a specific unit enters the trigger, well all you do is give the specific unit a name, in this case UNIT1. Create a trigger, set it to BLUFOR (if the unit belongs to blufor) and in the condition field add.
This && UNIT1 in thislist
Next create the enemy unit and give it the name ENEMYUNIT1 and hide him away from the action. Now instead of adding the code to the INT field of the enemy unit you add it to the triggers On Act field so it looks something like this.
nul=[ENEMYUNIT1,"A","random","min:",10,"showmarker"] execVM "ups-f.sqf"
Now when UNIT1 from Blufor enters the trigger ENEMYUNIT1 will move from his hidden location to marker 'A' and another 10 enemy units will randomly spawn within marker 'A'.
I've added a little demo at the bottom of this post if you want to take a look.
Turk.
Edit: Instantly move from his location to the marker!