My son wants to participate in his divorce hearing scheduled May 19 2014.He is serving in TDCJ in San Antonio Texas. Can he participate via phone conference or video?

He would need permission from both the warden, and the court, or have a lawyer in court to represent him.

Depending on the policies of the court where the divorce hearing is being held, and of course of the prison (or jail, or whatever the TDCJ is), he may be able to participate by telephone. As Talaniman suggests, you probably should hire an attorney to arrange this.