following the instructions in the wiki returns the following after running layman for the first time.
# layman -f -a kolab
* Failed to add overlay "kolab".
* Error was: Binary /usr/bin/svn seems to be missing! Overlay type "svn" not supported. Did you emerge dev-util/subversion?
perhaps it should be updated to say
emerge layman
emerge subversion
echo "source /usr/portage/local/layman/make.conf" >> /etc/make.conf
layman -f -a kolab