Good luck.
I only could say that it's somewhat close to my goals, my plans are to make a POSIX environment subsystem for my NT-like kernel.
It would consist of
1) dynamic libraries implementing posix calls either directly or doing needed preprocessing and passing them farther, to the "default" WinAPI-like subsystem (always on subsystem) libraries, or "native" dll (ntdll.dll).
2) support processes dealing with making the environment look like unix for posix programs. this could involve many tasks I am not even aware of right now.
3) kernel extension driver implementing the needed system services (syscalls) too foreign for NT (fork() or whatever() x^D). as well as kernel part for signals (APC).
NT is highly asynchronous in its nature so I might face similar problems you mentioned. I am planning to make my PussyX (the name :^D) as posix-compliant as possible, but not more.
It's all dreams for now. *sigh