The below enables OSX style copy and paste between a headless X11 desktop (running on a Linux VPS using fluxbox WM and tightvncserver) and OSX using an OSX VNC client.
It works by remapping X11 keys used by xterm and X11 apps to match OSX command-c and command-v copy and paste. Also enables VNC clients to copy and paste between the OSX and X11 desktops. Note that copy paste works both ways when using the RealVNC OSX client, but with Apple's Screen Sharing you can only paste an X11 copy to the OSX desktop (not vise versa) because it doesn't like autocutsel or Linux or something.