Edit /etc/rc.conf and put this line in it

devfs_system_ruleset="root"

Create /dev/devfs.rules with this ->
[root=100]

add path 'cd*' group operator mode 660
add path 'acd*' group operator mode 660
add path 'pass*' group operator mode 660
add path 'xpt*' group operator mode 660
add path 'uscanner*' group operator mode 660
add path 'ppi*' group operator mode 660
add path 'ugen*' group operator mode 660