the classic model is the Salkovskis (1985) (referenced below). I have a feeling he did an updated version incorporating safety behaviours, but essentially it's the same model and you can adapt it as you formulate collaboratively with your client. It's fairly straightforward (assuming you are familiar with/trained in CBT) although I would echo the usual concerns about making sure you have a supervisor qualified to help you to use these interventions. I wrote a case study recently so have pasted some useful refs below.
If it's a more complex case I find the chapter 'the devil's in the detail' by Sakovskis et al very helpful in (Treating Complex Cases: The Cognitive Behavioural Therapy Approach (Wiley Series in Clinical Psychology) [Paperback]).
good luck and hope that helps,
Foa, E. B. 1996. The efficacy of behavioral therapy with obsessive-compulsives. The Clinical Psychologist, 49, 2, 19-22.
Goodman, Goodman, Price, Rasmussen et al. 1989. The Yale Brown Obsessive-Compulsive Scale. Archives of General Psychiatry 46: 1006-1011.
The National Institute for Health and Clinical Excellence. 2005. Obsessive-compulsive disorder: Core interventions in the treatment of obsessive-compulsive disorder and body dysmorphic disorder. Clinical Guideline 31, London.
Obsessive-Compulsive Cognitions Working Group. 1997. Cognitive Assessment of Obsessive-Compulsive Disorder. Behaviour Research and Therapy, 35, 667-682.
Salkovskis P, 1985. Obsessive-compulsive problems: a cognitive behavioural analysis. Behaviour Research and Therapy, 23, 571-583.
Salkovskis P, R Shafran, S Rachman and M Freeston, 1999. Multiple pathways to inflated responsibility beliefs in obsessional problems: possible origins and implications for therapy and research. Behaviour Research and Therapy, 37, 1055-1062.
Wahl K, P Salkovskis & I Cotter, 2008. ‘I wash until it feels right’: The Phemonology of stopping criteria in obsessive compulsive washing. Anxiety Disorders, 22, 143-161.
Wells, A. (1997) Cognitive Therapy of Anxiety Disorders: A practical guide. Chichester: John Wiley & Sons.
Kintsukuroi: 'to repair with gold'. the art of repairing pottery with gold or silver lacquer and understanding that the piece is more beautiful for having been broken.