At the top, under the commands above the boffs, is an option for "rally" I believe. Click that. It will let the AI move to that spot and stay put. However, off the top of my head, I'm not sure how to undo it other than die.
i think you are talking about rally point, but i need each of my away team to stand in different spots. when i use rally, all go there. i think it is the same way you are able to sit in a chair, but again, i have messed up all my key binds and i'm not sure how to bring up the curser.
since i use my arrow keys for ground movement I mapped 'S' and 'W' for setting and clearing rally points respectively. As far as using the UI for setting/clearing, just right-click the same button you used to set the rally point and the team will come running back to you (provided they dont fall into some giant hole in the ground that they should have seen).
Edit: there is no way to map keys for any one boff (that I'm aware of). There is however a UI button next to their char portrait that you can click to set a way/rally point for them and right-click or use a clear all key to bring them back.