I was not comfortable being touched and one T and I worked on that very thing together :-) She had me shake her hand as I left each week then we graduated up to safe hugs. It was still scary for me but the "practice" did help as it often does with most actions.

I wouldn't go into "boundaries," I would just stay with how you're uncomfortable with being touched and would appreciate it if he didn't touch you at this time, that the closeness is not helping you but it isn't something you wish to work on at this time.