(...)
Ahh, right. Out of curiosity what toolchain are you using to build your
stage 1 cross compiler?

It would be nice if we could avoid it; GHC depending upon a library has
the very unfortunate effect that any user code also needing to link
against GHC or one of its libraries now has no choice in the version of
that library. We go to some lengths to try to keep the dependency
footprint of GHC small for this reason.

(...)
> Named pipes have also crossed my mind but I'm not sure how well they're
> supported by wine.
>
It would be great if there were some way we could make this work with
named pipes. Not only does it side-step the dependency issue, but it
feels like the right way forward.

Named pipes would solve your issue, Just don't forget to set the proper ACL on the pipes.

Cheers,

- Ben