there are a lot of ways you can pull this off.
the first and best way is buy a remote start that is made for a manual. these hit the market in retail stores about a year ago. there is a process you need to do that have about 5 steps, basically you do a valet take over (remote start it while the car is running) then you get out lock the doors and then turn the car off by the remote.
if the door is opened between you getting out and the next morning you remote start it, then the remote start will not work.
the second way, a little more old school, is you take 2 springs and some rubber spacers.... put the springs across the tracks where the shifter would be if it is in gear in front across the 1,3,5 and back across the 2,4,r... you run a wire to the hood switch (which keeps it from starting with the hood open) and if the shifter is touching the springs it will ground out the wire the same way the hood will if it is open.
the third way is a little more daring, but dont let people touch your car and make sure when you start it you can see it. i have been installing remote starts for 5 years and have done a number of all three of those in a number of cars, of course the first one is the only one i would do for a customer, the others were just for friends.
a lil update, i found a tech site that says there is a yellow/orange wire on the engine side of the firewall, i assume it is on the passenger side since there is nothing of the wire sorts on the divers side IIRC... so if it works ill let you know.