Go to the "parameters" section of wmt and tell google to ignore the parameters
From my experience, using Parameters handling at WMT isn't much of use if you want to ensure Google doesn't count those URLs that carry specific parameters. It is just a directive, and Google may choose to act on its own volition. More often that not, I have seen Google neglecting the directive given.
You can indeed use a wild card in robots.txt something like you describe could be tested in wmt
It will only help in avoiding new URLs getting indexed, but the ones already in the index, will continue to be in the index.
tkchinese, as far as I know, finding a way to add robots noindex tag is the only workable solution, if that can be managed. Else, try your luck with parameters.