I am looking to use intraday entries within the RSI Rotation script but am not sure if it is possible. More specifically, I want to use market orders to buy on a one tick break above the previous 5 minute bar high only if that price is x% below the previous day's close. This could also help with time priority in that if many stocks qualify for purchase on a particular day, only the first few that meet the criteria would be executed. Is any of this doable using WL version 6.1?

It should be doable (in any version, but not currently in a Streaming window). You can run it in a static Strategy window or in the S. Monitor.

Is this possible to simulate or would the test results using intraday entries based on 5 minute bars as stated above not be reliable? And could the time priority be incorporated into the backtest using intraday data?

Symbol rotation code includes priority by default because it should specify the entries and exits (or none) on any given bar - in backtest or realtime.

Reliability primarily depends on the data provider, but I can't remember trying something like this in the S. Monitor. Assuming Fidelity (currently), since you'll be executing on a primary symbol, the problem here will be updating the entire DataSet one symbol at a time; at approx. 3 seconds per round trip, that's too slow for more than a 10-symbol DataSet.

What's required for an intraday strategy like this one is a method for a provider to update all the [secondary] symbols in the DataSet nearly simultaneously. Fidelity is planning a data improvement in this area, but it's still only in a planning stage.

Okay so this isn't possible yet in realtime. How about in a backtest though?

Well, sure. Why wouldn't it be possible in backtest?