You can defeat the Passlock I and Passlock II anti-theft systems by using a DEI GM 555L Passlock Remote Start Interface (about $25 on ebay). You should be able to run the engine.
Here's their description:
THE 555L GENERAL MOTORS PASSLOCK INTERFACE MODULE IS USED WHEN INSTALLING REMOTE START PRODUCTS IN GM VEHICLES EQUIPPED WITH PASSLOCK I AND PASSLOCK II ANTI-THEFT SYSTEMS. THE 555L PROVIDES EASY INTERFACING WHILE MAINTAINING THE INTEGRITY OF THE VEHICLE'S ANTI-THEFT SYSTEM. THE 555L INTERFACES WITH THE PASSLOCK SYSTEMS BY PROVIDING THE PROPER RESISTANCE CODE (R-CODE) AT THE APPROPRIATE TIME. THE 555L WILL ALSO PROVIDE, WHEN NECESSARY, A NEGATIVE SIGNAL TO THE BULB CHECK WIRE. THE 555L HAS NO EFFECT ON THE PASSLOCK SYSTEM WHEN THE REMOTE START IS NOT IN USE THE FACTORY PASSLOCK ANTI-THEFT SYSTEM WILL REMAIN FULLY FUNCTIONAL.
