UTSD has a predental day, registration opens Jan. 26th at 9am. The link to register is here:
http://houstonasda.com/predental-day/ I highly recommend it, I did it 2 years ago... 7 of the 34 people got into UTSD. You essentially have a mock interview with students as well as faculty members. You'll also get the chance to review your personal statement with some of the students and get tips from them.
In terms of shadowing, you would just e-mail Dr. Galindo or one of the admissions coordinators and request to shadow a student for a day. Certain days are better than others so just message me privately if you are interested in that.