First, make sure that you have hfsprogs installed. Example installation command:
<code>sudo apt-get install hfsprogs</code>
Next, mount or remount the HFS+ drive; commands need to be as follows:
<code>sudo mount -t hfsplus -o force,rw /dev/sdx# /media/mntpoint</code>
<code>sudo mount -t hfsplus -o remount,force,rw /dev/sdx# /mount/point</code>
Finally, if the drive was improperly unmounted or has otherwise become partially corrupted run fsck.hfsplus (provided here by Jayson) as such:
<code>sudo fsck.hfsplus /dev/sdx#</code>