To answer the original question:
Internal consulting is quite a small market and you wont find recruiters specialising in this. Best bet are the leading consulting recruiters as they are in this market on both candidate and client side.
Also look for agencies that have advertised internal consulting roles in the past. Sometimes they will try and place rejected candidates in other roles and will have a contact list based on this.
I should say that now is not a great time. I tired of life on the road myself and returned to industry. However having been made redundant I am now sitting at home....and not finding much to apply for let alone getting interviews.