In theory, any person can just make a thread in the MM section and be an MM, but getting people to use you as a MM is the tricky part, I guess you should try to get known in the community and gain some trust.
You should become more active in the community, make some good friends, gain trust & respect from making trades in the market etc.
Once you have alot of people's respect, you could try opening up a free MM service, and get your friends to start using you and also vouching/spreading word about your service to gain some more customers. Becoming a successful middleman is quite a long, bumpy road I am sure, but it can be done with dedication and committment!