Yes I have installed it in a manual before but you need to find a way to complete the circuit on the clutch (neutral safety switch). I used a toggle switch and it doubled as a kill switch if I didn't want anyone else to start it. It has to be in neutral to start though if you try to start it in gear it's not going to end well.
I called around to local stereo/alarm shops regarding having remote start installed. They all passed on it (including the dealership) because the way they explained it a whole harness has to be replaced which might affect other electrical functions.
Mine is a 2.4 automatic, not a stick which is even trickier.
Where are you guys having this done?