The Manhole PC-Engine came today. Funny how it takes only a day longer to come from Japan than Utah.... Anyway, no luck trying to extract the files yet. "dumpcd" isn't able to dump the pseudo-audio track to an iso. Perhaps another program will help.... In the end, I'll have to write an extraction program for the data like with extract_tg16_loom.
Better news is that The Manhole New and Enhanced is now working in ScummVM! Yays! (Though, my only contribution was the minor detection changes, and had almost nothing to do with it actually working... :P). Well, it works as far as I can tell anyway (it starts and shows the first few screens :P).