I found the XBMC auto-updating capabilities severely lacking, as a result, only raspbmc is supported (openelec has no way of installing the required lxml package).

To use on any linux system, ensure python's lxml and requests are installed.

1. install and start raspbmc
2. select "Exit" from the shutdown menu
3. when prompted, press ESC for a terminal
4. login as "pi", password "raspberry"
5. type in the following command wget -O- http://mbr.github.io/xvisi | sh
6. wait for a reboot and enjoy

Unsupported and not-up-to date: https://raw.github.com/mbr/xvisi/gh-pages/repository.xvisi.zip