CS,
I'm not sure of the exact procedure to do this.
I don't think any instructor is going to simply sign you off, without seeing you fly. Look carefully at the wording...
"a logbook endorsement from an FAA instructor who has found the person proficient"
Thus, I would say you would have to fly with this instructor before you get anything done.
Like I said, I don't know for sure. This is only my 'logical' conclusion to my reading of the FAR.
You need to check with a FSDO or someone else who's actually done it.
cl12pv2s