DayPilot.Month.multiselect.add(e, dontRedraw);
For bulk operations, use dontRedraw = true and call multiselect.redraw() after all changes have been made.
Select an event manually in the custom EventClick handler.
.aspx
EventClickHandling="JavaScript" EventClickJavaScript="eventClick(e)"
JavaScript
function eventClick(e) { dpm.multiselect.add(e); }