I think Linux doesn't support writing to UFS2 filesystems (at least according to wikipedia).
You can try the following:
How to mount a 'read-only' filesystem read/write? (top)http://www.netbsd.org/docs/misc/#read-o ... read-write
Use mount(8)'s -u (update) switch: 'mount -u /'. More than likely, you booted single-user which mounts the root filesystem read-only by default. This gives you a chance to run fsck by hand before bringing the system up into multi-user. One other way to mount all the filesystems in /etc/fstab as read/write is to use 'mount -a'.
However, the best way to do this is to go into multi-user mode by exiting from your single-user shell. This will mount all of the filesystems in /etc/fstab in whatever mode they are listed.
If you can't do that from psSense, try it with a NetBSD liveCD.
Download Ultimate Boot CD v5.0
Use Parted Magic
for handling all partitioning task: http://partedmagic.com/