klei.604: There is no way to do this in the game. The only sloppy workaround is to run out of movement or speed points just at the sweet spot you want which is probably far from what you want to achieve.
The trick is to select two units and let them move in formation. The 'leader' (yellow/white boxed) will move where you click the unit, and the rest of the units follow in formation relative to the leading unit. The formation/multiple units will stop when one of the units runs out of movement.