Hello gprime87, and welcome to OFPEC!
This is a conundrum almost as bad as the "how do I get my helicopter to do X or Y?", and it's grown especially bad with Arma 2, which introduces .fsm-based combat scripts (where the units go from cover to cover and use bounding overwatch to move under fire). This is great when you're actually under fire, but not so great when you want people to just MOVE IT. There's been requests for an AI-override button called something like LEG IT which would force the damned muppets to just do what they're told instead of jumping up and down and crawling around and running in circles.
Basically, when they go into combat behaviour, they become very unresponsive to commands. This can be a problem. My only suggestion, at this point, is to make his behaviour Careless. Now he shouldn't hopefully go into combat mode (although he won't react to enemies either) until he's a part of the player's group. Try it out and see if it works.
It is possible to force a unit to go from a to b in a straight line via script, but let's at least try some alternatives before that. You are patched up to the latest 1.57/1.08 right? Some of the latest patches really helped with the whole prolonged combat mode shtick.
Wolfrug out.