Hi leonb
Got it working
Copy zip to external drive, launch XBMC and choose to install addon from zip file (If it complains about dependency problems, just install again).
After installing, go to XBMC Apps and launch "Frequency Switcher". Select "framerates" and choose the ones you want to use, or modify/add your own before saving the configuration. Now go to service and choose the framerate you want to default to on movie start and exit. Keep notifications on so that you can see what XBMC is adjusting the framerate to. Save configuration again and relaunch XBMC to start the service.
That's it!
Download link ->
https://mega.co.nz/#!CFU0TAJS!-opaGMsAdkAh3S_yI5414GlFbJE26E8piqrt3tTfblE