However not all hope is lost. The idea you want does come up from time to time. Also it seems that there is something out there called userfs, which is a kernel interface to user level programs that implement a filesystem.

Seriously I would do a good search on this and see what you can turn up. I doubt that any great solutions exist, but you are far from alone in wanting this, and you should be able to scare up something.

And BTW, good luck. :-)

EDIT
FWIW my personal opinion on the question is that it is something a lot of people want. Just because a pure Perl solution would be a bad fit doesn't mean it isn't a good question to ask. Indeed if jettero does manage to track down and play around with userfs, I would love to see a Perl interface built. Perl may not be a good fit for a kernel, but it is great for building interesting prototypes...