If your Importacular package includes both the Event Participants data destination as well as a second data destination that allows you to import an additional constituent (Individual Relationships, Organisation Relationships, Solicitor/Canvasser Relationships or Tribute), it is possible to set up your Importacular template to link the Event Participant to one constituent and add a donation to be linked to a separate constituent as well as the Event Participation.  See this demo showing this process in action using the Tribute data destination.  For a demo using the Individual Relationships data destination, see this video.