According to the American Psychiatric Association Depersonalization Disorder is only supposed to be diagnosed when no other disorders are present. When depersonalization is secondary to a psychological or physical cause it can be called depersonalization syndrome or depersonalization for short. The APA have continuously flirted with calling it depersonalization-derealization disorder, as it's currently called in the latest edition of the DSM. Depersonalization Disorder has no officially approved treatments. All treatments are off-label or experimental. For this reason it can be said no official treatment for Depersonalization Disorder exists. Coolwhips's advice, however he arrived at his conclusion, is the best because it's the most realistic and current.
As for comorbid disorders, which may be primary causes of depersonalization in many cases, these often require intervention. For example if a patient has depersonalization as a consequence of using marijuana or suffering from panic attacks these are problems which can be addressed. Many sufferers fall into the trap of ignoring their comorbid problems because they're hopelessly obsessed with their symptoms and anxious rumination.