Okay, I got Venom to compile. Irrlicht does in fact run, but I had to do some modifications to the Irrlicht Linux device to make it work.
The XFree86 code was assuming that the XFree86-VidModeExtension module existed. The Apple XFree86 server apparantly doesn't come with this.
I modified the code to make sure it doesn't try to mess with VidModeExtension if it doesn't exist. That got Irrlicht to the point where it was at least running.
It seems to run stable, but there are some issues with loading models. I assumed this would be the case.. I'll bet there's problems with endianess.
I'm gonna play around and see what I can do to make loading meshes work...