Partitions consist of slices and you need to mount them....
For example, if ad4s4 is your FreeBSD partition, then
you need to mount ad4s4a under /
EDIT: ad4s4b will be swap
and ad4s4d to whatever is last one you have will be /usr /var and others.... depends on how you configured system
here;s my fstab:
- # Device Mountpoint FStype Options Dump Pass#
/dev/ad4s1b none swap sw 0 0
/dev/ad4s1a / ufs rw 1 1
/dev/ad4s2d /home ufs rw 2 2
/dev/ad4s1e /tmp ufs rw 2 2
/dev/ad4s1f /usr ufs rw 2 2
/dev/ad4s1d /var ufs rw 2 2
/dev/acd0 /cdrom cd9660 ro,noauto 0 0
/dev/acd0 /home/killasmurf/DVD cd9660 ro,noauto 0 0
what filesystems are ad4s1 and ad4s2??
and where exactly you'd like them to be mounted?
basically
mount /dev/ad4s1d /usr/somedir
mount /dev/ad4s1e /usr/some_other_dir
mount /dev/ad4s1f /usr/some_other_dir_