Some days ago, I got a requirement of giving access to 3 users to my SVN repo over ssh.

#groupadd dev
#useradd -g dev auser
#useradd -g dev buser
#useradd -g dev cuser

Then set the passwords for each user.

For SVN, update changes, you need to have the working copy owned by dev group

#chmod 0775 -R myworkingcopy
#chown -R apache:dev myworkingcopy

For svn post commit hook

#chown apache:dev post-commit
#chmod 0755 post-commit

The point here is that the user committing the changes should have the write permissions to the working copy and execute permissions on the post-commit hook

and all is good.