There are 4 preset MACD scripts within Optuma. To see them go to Settings - Script Manager and search for MACD. The results will be displayed, and you can click on each to see the underlying script being used:
If the criteria you are after is not listed here you would need to build a custom script.
Based on your example it looks like you’d need to build a custom code, as you’re looking for crossovers to occur under a specific value.