How can I get automated alerts based on when RSI, MACD, etc. cross mid-line?

Trading Systems Expert Advisors and Automated Trading
1

What kind of logic can I use to tell charting software to produce an alert when a bunch of indicators (e.g. RSI, MACD, Stochastics, etc.) all happen to cross their respective mid-lines within x minutes of each other? Say the 30 minute time-frame version of each indicator.

Thanks.