Thanks!
I tried to build it, but failed.
The build process does not just need Masm, but - at least - also the DM C compiler.
When I launch build_optlink.bat, it starts to compile, but after a few modules, when trying to compile ntio\printf.c, it complains that file scio.h cannot be found. Actually, that file isn't included and it's also nowhere in the DM installation directory. So I gave up for now.