Don't know if you are looking for an alternative software package to accomplish this, but RT Investor at www.linnsoft.com is set up to quickly backtest on hundreds of stocks at once.
Personally, it has always been a mystery to me why Tradestation gets so much business when one has to sit there and run a stock at a time, or rig something to help it along. There are other alternatives.
There are tens of products that can do portfolio testing for Tradestation, but seems more people are waiting to see when Tradestation offeres build-in portfolio tester Because that will be more reliable than 3rd party add-on softwares and due to be out early this year.
You can backtest in Tradestation radarscreen actually. You have to generate the kind of report you want for yourself via writing to Excel files or via the indicator prints. It is crude but quick. You have to make the parameter changes by hand so you can do successive approximation in that regard and converge on a solution. Getting the results out of radarscreen in some kind of usable format is the trick. Once you get on to how to work it it's a good enough way to go.