I copied the below from the HP Tuners forum. I have followed the same guide to disable the VATS in my 04 LS, should work for you also:

To disable VATS you must do the following:

1. Set the VATS value to "PWM"
2. Set DTC P1626 to "3 - No Error Reported"
3. Set DTC P1629 to "3 - No Error Reported"

Additionally you might need to set
4. Set DTC P1630 to "3 - No Error Reported"
5. Set DTC P1631 to "3 - No Error Reported"