[Support] Mass Effect Issues

So I've got Mass Effect working with the controller by running Steam in Admin (and putting up with that bloody compatibility warning popup every time I start Steam). But the trackpad will only work as a mouse if I change the in-game settings to software mouse.

Downside here is that if I fire or use the activate key while the mouse is moving, it'll randomly spaz out and flick up to the ceiling or somewhere behind me; even with the sensitivity set so low that it takes a full swipe for a 90^o turn. I can just make sure I don't touch the right pad while firing or pressing the use key, but that really takes you out of enjoying the game when you have to keep it in mind all the time...

Anyone else have issues setting Mass Effect up with their controller or can think of something incredibly obvious that I've missed that'll let me stop having to be so deliberate with movement and action in the game?