Comfyshoes - I know that the histrionic personality disorder treatment requires significant psychotherapy which includes cognitive behavioral therapy.
People with this disorder have to begin to understand that drama is not required to have a fulfilling relationship and developing a level of happiness has to do with shifting their needs and making someone's else's needs more important than their own.
The quality of your relationships does determine your level of happiness and overall satisfaction in life. This is why these types of people are often depressed because they don't know how to function properly in a relationship.
It takes a long time for a patient to get to this realization and many times the histrionic patient actually develops feelings for the therapist because the therapist has to “Rescue” the patient which is how the patient views the therapeutic sessions.
Boundaries and a very non emotional tone are best when dealing with a patient with this disorder.