WineLib and DLLs

I'm writing a WineLib DLL that makes calls in my own Windows DLLs
(not Wine's DLLs).  I have the header files for those DLLs, and the
Windows binaries for them.  How do I link to them?  Do I need to wrap
them in spec files?  What do I need to put into my Makefile.in?

There are instructions in the WineLib docs about binary DLLs, but
they seem to be talking about pretending a Linux library is a DLL,
which is not what I want to do.

-Steve