I would like to run clamscan in batch mode and trap the errorlevel variable so that it returns the total number of virii found. Is that at all possible? Or is there some other clamwin pgm I should be using?

Clamscan will only return whether it found a virus (1) or not (0), or some error code. It will not tell you how many virii were found. To count such a number, you will have to parse the scanner output.