actually I got a reply from McAfee presales team regrding my questions as below:
can the MVM scan the IBM AS400?
yes it is supported
Does MVM support google web Toolkit(GWT)?
GWT consists of several modules and this is pretty broad question. We don’t certify our product to support GWT but we do have support AJAX ( i.e. we don’t re-render page base on AJAX communications but we do submit AJAX requests to fuss with the web application) which is probably what’s pertinent to the question here.