I believe it's general rush, but if I were you, I'd bring an ID just in case.
ETA-Straight from TalkinBroadway.com: Student Rush tickets are available for $25, two hours before curtain, with valid student id, for cash only. Updated On: 10/9/05 at 08:21 AM
I did the rush for Musical of Musicals. You can basically get there anytime before it starts because they don't sell out. The tickets are 25$ w/a student i.d. 1 ticket per i.d., but they seem layed back at Dodger Stages. Enjoy!