Why are you saving the file to a temporary location prior to printing it? Why are you not saving it as a unique filename each time and then using the File I/O -> Delete File action to clean it up after it's done printing?
Sam
PS: I have already written a "File Runner" action block for MII and it's on the MII Wiki here (Customization - xMII - SCN Wiki) called File Runner Custom Action: http://scn.sap.com/docs/DOC-22962 and the associated document has the complete code of the action.