Yes, it's easy to make, A pin of a serial port or parallel port or also game port is usable to do this.
An hardware connexion on a keybord controler to simulate a Key is also possible.
A very small electronic module to interface between the 12V of the car and the signal of the port used and a software timer to check his state.
We must only define the better solution between all this.
One signal of the parallel port not used for control the LCD is a good and very easy solution I think.
I check that and give you news when I have made the drawing of the "électronic module" who will be simply a relay or a transistor with some resitor I think.