old thread, but basically the short answer is likely to be no.
TradeStation is bundled with the TS brokerage & data services, and automation with TS usually means orders get plugged straight into the TS brokerage. No prop shop would work like that because they obviously provide their own brokerage services off the back of the leverage they also provide.
Aside from the fact that TS is probably 50x more expensive in commission fee's than a typical prop firm.
There are ways to get orders OUT of TS and patched into other API's but the data quality/speed/stability of TS is not really good enough on its own, never mind adding extra peices of software into the order routing mix.
The best way to approach automating a strategy with a prop firm would be to write your code for the Trading Technologies API, since this is the standard platform used almost everywhere