Check out the Museum Studies program at Cal State Fullerton. There may be
intern positions in the Gallery on-site. I took a few of the early (12 years
ago) classes regarding interpretive studies, but majored in Enviromental
design. Seems a stronger museum program today. They're program is listed on
the Net under word search "Interpretive."
Art Center has some exhibition design classes, but this is a private program,
and I don't think there are any intern positions.