Client DN in HTTP header

I'm it a bit of a crunch and I am nowhere close to an iRules guru but I'm in the odd position of having to walk someone else through building an iRule on an F5 that I cannot . Can someone provide me with an iRule that would take the Client Cert DN from a 2-way SSL session and insert it into a header called "client-dn"???

 

v/r

 

Joe