It's not directly supported at this moment.
However, it's possible to use one of the ajax libraries that support drag&drop and register the event div as a drop target using AfterEventRenderJavaScript. The div reference is available there in "div" variable.
See also:
http://api.daypilot.org/daypilot-calendar-aftereventrender/
http://api.daypilot.org/daypilot-scheduler-aftereventrender/