[Zope] how to migrate from TextIndexNG to TextIndexNG2

I'm importing (trying to) a plone site whose catalog has TextIndexNG indices into a new zope which has TextIndexNG2, and getting all kinds of errors.... is there a *real* way to migrate from TextIndexNG to TextIndexNG2? Can I have both installed at the same time? (errors are of the kind: 2003-12-19T16:13:59 ERROR(200) Catalog catalogObject was passed bad index object <TextIndexNG instance at ee17540>. )