Although you probably already know you shouldn't install a remote start not designed for a manual trans truck, what you need to do is hop under the dash, and at the clutch there should be a switch. Take a multi meter and test the wire, check which one you see a change in, after you do this you will need to hook the status wire, if its a DEI remote start (Viper, Avital, Python, etc.) it is a blue wire with a white tracer. this wire puts out a positive signal, if your clutch test as needing a negative signal, you'll need to use a relay.
Good Luck, and remember, always keep it in neutral.