[plt-scheme] MzScheme feature question

Hello,
   A few friends of mine and myself are entertaining the idea of
extending the MzScheme oskit kernel and using it for serious operating
systems fun (read: "non-academic research", aka, a hobby project)..
However, we really want the ability to run multiple Scheme environments
concurrently, by having the mzscheme VM step through one bytecode per
program at a time (eg. a sort of round-robin scheduler).

I was wondering if any of the mzscheme developers could shed some light
on just how difficult this process would be to set up? 

TIA

-Ryan