[cadgear]

I don't know of a way to reset the VATS module, as it is programmed to permenantly store the first code it gets (i.e. the first time the car's cranked). If it was a police model, then the ignition is jumpered to bypass the vats module, and replacing the ignition switch might activate it.

Although before jumping to conclusions, does the SECURITY light do its little jig when you try to crank it? If not, you may just have a borked switch (or improper installation).