You could try building it from source. It needs the os4 threads library, but you might be able to link it against gnu pthreads or something if you built that.
It also might require some newer reaction features than are available on 3.9. I had a very quick browse of the amiga source, but nothing more.
(There are a bunch of other libraries you will need to build to link against too).
no idea if it uses other os4 features too.
