I just spent 5 hours reading about manual transmission remote starts. There are many different issues. The biggest one is obviously an accidental remote start, in gear, parking brake off/worn/broken/partly engaged and destruction of property or, god forbid, loss of life. Alas, there are some that are made for manual transmissions with a very complex sequence to arm the device. One involved; park, windows up, shift to neutral, pull parking brake, release clutch, turn key off and take out (which leaves your car running), open the door, get out, close the door. Once you close the door, your car locks, then shuts off, which arms your remote start, which prevents you from leaving it in gear; otherwise, your remote start won't be armed, and the remote start button will do nothing.
-Eric Smit