The stochastics with long-term EMA filter strategy, is available for download at here.
Once downloaded, from within the NinjaTrader Control Center window, select the menu File > Utilities > Import NinjaScript and select the downloaded file.
You can review the indicator's source code by selecting the menu Tools > Edit NinjaScript > Strategy from within the NinjaTrader Control Center window and selecting the strategy "StochasticsColby".