http://www.kiya1.de/images/Divexp_Josieend.jpg.html

Please, look into this link and scroll. I could curse and polymorph her at survivor curse lvl 2 and 5.

Are you a warrior? I don't know why, but I had a save from a Polish gamer and could not curse Josie with her warrior. My char was a mage.

You have to click on Josie several times to curse her, as this skill is cumulartive. The more you curse (by clicking) the more you lower her resistances to polymorph her.