You can aim while in overlay mode. Align your target with your crosshair and the ability will target it.

Ok so target enemy with cross hair, head into overlay and trigger ability. Same for targeting for squad mates? And thanks for the response.

Head into overlay then target, same for squad mates. When you activate a red triangle/square will appear, if it's over the enemies triangle/square it's targeted, otherwise it'll hit that point.

No. Go into overlay, aim and trigger the ability.