That an interesting and important question, and I am pondering over whether to answer it here, since as you say, its not really an EMDR question. Its a dissociation question, but what makes it marginal is the fact that you are using the EMDR structure. Still, I am going to demur, lest I end up talking outside of EMDR about dissociation.

Colin Ross has published this book ---2nd edition of his book on dissociation, which is Dissociative Identity Disorder: Diagnosis, Clinical Features and Treatment of Multiple Personality. New York: Wiley. 2nd Edition, 1997. In it he has a wonderful list of negative cognitions that are typical in DID. That's a great place to start. Also, Joan Golston has a similar list of themes. You might benefit from being on the ISSD discussion list, a very worthy organization. Joan is there, as are many other well respect dissociation experts.