The eScript below helps you to invoke the WF process asynchronously. Like this we can call any WF process asynchronously from the Business Service / BC / Applet scripts.
var oBS = TheApplication().GetService("Asynchronous Server Requests");
var psInputs = TheApplication().NewPropertySet();
var psOutputs = TheApplication().NewPropertySet();
var psChild = TheApplication().NewPropertySet();
var sObjId = this.GetFieldValue("Id");
psInputs.SetProperty("Component", "WfProcMgr");
psChild.SetProperty("Object Id", sObjId);
psChild.SetProperty("ProcessName", "Sample WF Process Name");
psInputs.AddChild(psChild);
oBS.InvokeMethod("SubmitRequest", psInputs, psOutputs);