I think your options are pretty limited. I know that the bus (www.airportbus.com) will take you to Universal, Knotts, etc, but I don't see magic mt listed. The only time we've went there we used a rental car. We didnt want or need one for the whole trip, so we just did a one day rental. They brought it to our hotel, and picked it up when we were done. Worked great.
If it takes you 2 hours to get from disneyland to Magic mountain then you stopped to get lunch.
a hour is a good guess actually and I normally never agree with yahoo. but in the thousands of times I have drove this it took two hours only once and it was because traffic was very bad.
All that being said with out a car not really any cheap ways to get there. maybe try and find others that will be there the same and car pool