Can vistaril (hydroxyzine) be used to treat OCD symptoms, particularly the obsessive portion? If so, to what extent?

No, mostly. Not usually. Vistaril is used as an anti-anxiety medication, but it works for people mostly because of it's convenient side effect of sedation. If someone really has ocd, vistaril is unlikely to target the main issues. Ssris like prozac, paxil, (paroxetine) zoloft and therapies like cognitive behavioral training are much more effective, i would recommend you look in that direction with your md first. Be well.