Using KAMA with the price movement of a stock or ETF

I think you mean, when close crosses below the KAMA.

Stockcharts uses the "x" operator for crossovers, but it means "crosses above". The left term crosses above the right term.

I this case you want "cross below", but to get that with the "x" operator , you have to think of it as the slower term (the KAMA) crossing above the faster term (the close), even though intuitively it seems to be the reverse.

[KAMA(10,2,30) x close]

The mechanics of Technical Alerts are explained here:

https://support.stockcharts.com/doku.php?id=alerts:alert_workbench

Cross over scans are explained here:

https://support.stockcharts.com/doku.php?id=scans:advanced_scan_syntax:crossover_scans