How far along are you? I'm the Nov EC resident breech expert, it seems.

I have tried:
Webster (find a *good* chiro at
www.icpa4kids.com)
Moxibustion
Laying on a slant board with ice at the fundus, heat/light/music down low
Swimming and forward flips in the water
Knee/Chest with rebozo work (2 MWs jiggling pelvis with rebozo)
Pulsatilla (200c every 3 days)
And finally a version. If you are not too far along, I would try everything else first and then the version, since it was quite painful.
As far as sitting on the ball, I think its ok, just avoid deep squats or anything that will prematurely force the baby into your pelvis, while you are still working on getting s/he turned.
FTR, nothing has worked for me, but I think I started a bit too late. I would start Webster at 30w (though I thought *was* doing Webster, but realized my original chiro was not doing it right) and the other stuff around 35w.
Good luck! I am finally at peace with the idea that my baby is not going to turn unless its on *her* terms, but seeing as she is settling her butt lower into my pelvis this week, there isn't much hope left of that.

If you want to chat more, feel free to PM me. I understand the emotions you are feeling, since I was planning a HB as well.