I looked into this myself awhile back. I have more info for Northern California since that is where I was living at the time. Mills College in Oakland has a program that I have heard great things about from someone I know who completed it and is now at UCSF. The only downfall is the cost. A cheaper option which I checked out is Cal State-Hayward. They have an organized post-bac pre-med program and the advisors seemed very good and helpful. It seemed to be a mix of people wanting to raise GPA's and people doing the requirements for the first time. You could also consider, if you just want a couple of classes, Berkeley Extension (though they may not have much upper division stuff) or trying to take a few classes as a nonclassified student at any Cal State campus. Some of the UC's, UCSC, Riverside, and I believe Irvine, will let you do this if you already have a degree as long as they have space, but it is usually a limited number of credits. There are also formal post-bac programs at UCSF and UC-Davis that you can look into. They both have requirements about your background and current GPA I believe.
As for Southern California I did not look very much but I do know that USC has a program and that Scripps also has one which I have heard good things about. Oh, and both the Scripps and Mills post-bac programs are co-ed even though they are women's colleges. San Diego State did not have a formal program but they will also let you do post-bac work or a second degree if they are not full, which in the year I was looking, 2001, they were. Hope that helps.🙂