In your map,
Create an area that you want to patrol (marker)
1. Select Markers (F6).
2. Double click the center of your zone you want patrolled. Try and chose the center as something memorable as you may need to relocate it later.
3. Give the area an appropriate name (patrol1, runway2, centertown). The easier to remember the better, it's worth noting down somewhere as they are a bugger to rename sometimes. We'll call it NUBBINS just so you remember it.
4. Select rectangle as the type
5. Set axis a and axis b as appropriate, 200 by 200 is a good start, but you can tweak it.
6. Press OK
Create a patrol group
1. Select groups F2
2. Double click on the map where you want them to start.
3. Select the type of group you want, remember OPFOR is essentially the ruskies.
4. Press OK
Associate the random script
1. From the map view, double click the leader of the group
2. In the 'Initialization' window, enter the following text;
nul=[this,"NUBBINS"] execVM "ups.sqf"
Now the final piece of magic, extract the attached sqf file into your save game folder file, which will be;
documents/Arma2/missions/yourmissionname
In that folder should be the sqm of your saved mission.
Credit for this script should go to Kronzky.
http://kronzky.info/ups/index.htm
my less ugly blog on this is on the new site..(hows that for a carrot?)