A more permanent cheaper solution is to place a pushbutton switch in where fuse number 3 should be in the fuse box, This means you will have to remove the siren so it doesn't go off all the time, and when you do remove the siren be sure to have something to muffle it as it has a backup battery and lasts about 30 minutes!
You will loose the function of your remote central locking but its a small price for mobility again!
First pull out fuse 3 in the fusebox near the drivers door, pop the bonnet and cut the siren wires, should be about 5 in total black in colour.
You wont need the siren anymore so if you want to dunk it in a bottle of water or smash it up with a large hammer do so now lol!
Install a push to connect switch, available from maplin electonics, in a convenient place, i would suggest passengers side of the steering wheel area.
Run 2 wires from the switch to where each blade of fuse number 3 goes in, use small spade crimp connections to insert the wires into the slots.
turn your key to accessory then as you crank the motor press the switch at the same time and your car will start up.
Hope this helps
Stu
Stuart Morgan - Neon owner, July 2009