If you still have P11 installed then you can still use all the techniques available to import it and resave it back into the Poser Library for P12 use.  There is the FBX import but I don't have too much confidence in that import method.  An issue I have observed is that not all morphs translate well through the DSON import method.  Simple hair seems to be no problem, the more complex, the more likely it will fail.