I don't know if this is feasible in your situation, but have you tried using ssh to connect to the remote host? SSH X tunnels work quite well and don't require any xhost nonsense. You'll probably have to give the ssh command a "-X" (or maybe "-Y") option, and it has to be enabled in the ssh server's config file, but it works a charm barring all that. (Of course, I haven't done it under MacOS. I'll try when I get home.)