Fairly simple, got talk to the Prof who like to work with and then if he likes you get to work. As soon as you hear from the guy give him an email saying you would like to meet him in person. It may take a while to get a one on one meeting sometimes be patient. Don't go asking for pay and financial support on first meeting. Work with him for sometime if you are satisfied then request him if he can support you.

It was done with multiple professors and administrators from department. It has changed since I started, and the experience for incoming graduate students is more personalized. It is now a longer event and you will be also somewhat interviewed by other students so treat the entire experience as an interview.