General

emerge subversion
emerge --config dev-util/subversion

create a group for svn

groupadd -g 1010 svngrp

edit /etc/conf.d/svnserve and change the group

#SVNSERVE_USER="apache"
SVNSERVE_GROUP="svngrp"

Start the service and add it to default runlevel

/etc/init.d/svnserve start
rc-update add svnserve default

Setting up access rights

Setting up a new repository. I currently create a new group for each repository and assign users to the group if they need read/write access.

1) cd /var/svn
2) mkdir foorepo
3) svnadmin create foorepo
4) chmod -R 770 foorepo
5) chmod -R g+s foorepo/db
6) chgrp -R svn-foorepo foorepo
(svn-foorepo is the group name that I created in /etc/group to hold the svn users)