That's a feature we added in the latest version of Vision Builder AI (2012), which will be available very soon.
Would it be a possibility for you to use the Run LabVIEW step to calibrate your image? If so, you can call a LabVIEW VI that sets the calibration using IMAQ Set Simple Calibration2, after the acquisition steps. Once the image is calibrated, all subsequent steps should return calibrated results, even if you're not using the VBAI built in calibration.
Christophe