MameHub has been mentioned elsewhere in the thread and while it solves a different problem (sharing the same MAME session) it still might be worth your time to get in contact with the developer, DigitalGhost. MameHub is simply the GUI/meeting place for ClinetServerMAME which you might find more relevant. Unless you hope to have your work accepted into the official codebase, CSMAME might be a good home for it.