Not sure why you don't want to use a workflow, but the out-of-the-box Ad-hoc workflow could be used since it very simple and doesn't require any development effort.
var workflow = actions.create("start-workflow");
workflow.parameters.workflowName = "jbpm$wf:adhoc";
workflow.parameters["bpm:workflowDescription"] = ;
workflow.parameters["bpm:assignee"] = ;
workflow.parameters["wf:notifyMe"]=false;
var futureDate = new Date();
futureDate.setDate(futureDate.getDate() + 1);
workflow.parameters["bpm:workflowDueDate"] = futureDate;*/
workflow.execute(file);