I'm not local, but we plan to do this on an upcoming trip, and I copied the following info from another posting somewhere:
OCTA Route 43 goes from Disneyland to Harbor and Orangethorpe in about 20 minutes, $1.25 per adult each way. Just find a bus stop on Harbor and head north about 3 miles, the bus driver will be happy to let you know when you get to Orangethorpe.
I went to
www.octa.net and was able to find the exact schedule and route. Looks pretty easy, and for my suburban kids, this will be an adventure in itself! I believe there is an In & Out as well as a Mexican restaurant close by, so we'll probably make a half-day outing of it. Hope this helps!