Take it as any other entity. You can trigger it with anything that has a "target" field in its properties...
And the target field? Select the entity you want to trigger the multi_manager, press Alt+Enter and a table will pop up... It will have all the entities properties (name, target, delaybefore target, etc.). So just enter the name of yer multimanager in the "target field" and walla! Your multimanager is triggered!