How to mount a HFS partition in Ubuntu as Read/Write?

First, make sure that you have hfsprogs installed. Example installation command:

sudo apt-get install hfsprogs

Next, mount or remount the HFS+ drive; commands need to be as follows:

sudo mount -t hfsplus -o force,rw /dev/sdx# /media/mntpoint

or

sudo mount -t hfsplus -o remount,force,rw /dev/sdx# /mount/point

Finally, if the drive was improperly unmounted or has otherwise become partially corrupted run fsck.hfsplus (provided here by Jayson) as such:

sudo fsck.hfsplus /dev/sdx#