The latest version of Vision Assistant 2011 SP1 lets you specify much bigger kernels, but unfortunately, they still have to be the same size in X and Y. Thanks for the feedback. We might consider letting the user specify different sizes in X and Y in a future version.
As Bruce mentioned, you will have to generated the code and do it in LabVIEW.
Alternatively, you can just create that VI from LabVIEW using the kernel you want, call it using the Run LabVIEW step, and still do the rest of your prototyping in Vision Assistant.
Christophe