Before starting this you should have MK-Livestatus up and running!

Updated to 1.1.12p3!

1. Download check-mk 1.1.12p3 from http://mathias-kettner.de/download/check_mk-1.1.12p3.tar.gz
2. % cd /tmp
3. % tar .../xzf check_mk-1.1.12p3.tar.gz
4. % mkdir /usr/local/nagios/mk-multisite
   or wherever you want to put it. If you change this path you also have to change/fix the config files
5. cd /usr/local/nagios/mk-multisite
6. % tar xzf /tmp/check_mk-1.1.12p3/web.tar.gz
7. % mkdir -p var/web
8. % chown -R www-data:www-data var
   (on Suse use "wwwrun:www" as new owner)
9. Download attached mk-multisite-etc.tar.gz
10. % tar xzf .../mk-multisite-1.1.12-etc.tar.gz
11. Install and enable "mod_python" in your Apache2, on Debian: apt-get install libapache2-mod-python && a2enmod python
12. % ln -s /usr/local/nagios/mk-multisite/etc/apache.conf /etc/apache2/conf.d/mk-multisite.conf
13. % ln -s /usr/local/nagios/mk-multisite/etc/defaults.py /usr/local/nagios/mk-multisite/htdocs/
14. % /etc/init.d/apache2 reload
15. Have fun :)

If it doesn't work have a look to etc/defaults.py (path names) and/or etc/multisite.mk

Feedback welcome ;-)