From the owners handbook for the VT it suggests the following.
Put the key in the ignition and turn to ON (instrument warning lights turn on), then press UNLOCK on the key while it's in there a few times see if the light stops.
1. Insert the key in the ignition lock and turn to the ON position (instrument warning lights illuminate). Ignore the alarm if it is set off.
2. Turn off all accessories (so as not to flatten the car's battery) and leave ignition in ON position.
3. Wait for 2 hours. DO NOT turn the key in the time. *Note that the security light stops flashing when the engine is ready to be started.
4. Turn the key directly to the start position and start the engine.
If you can get the engine started it is recommended that you visit a Holden Dealer to get the security system looked at, you may have to repeat this procedure every time until you get it fixed.
If your key is dead, try locking and unlocking the car doors from the outside manually may reset it as well. The commodores can be damned twitchy at times.