Yes - I did something very similar. I created virtual redirected printer (using Redmon EE) but used the 'temp file to printer' option to send the original job on to the printer once my EXE I'd specified in the REDMON parameters had finished running.
Then I created a VB 2008 EXE that received the options sent from REDMON EE - and it copies the temp PS file to a second location (for later processing into a PDF) - and then finishes - which in turn causes the print job to continue to the proper
Same as your's really - except you copy the file to the printer.
I'll have to look at mfilemon - never heard of it.