Here is a map from downtown LA to where the trail starts for the Bradford Ridge Path (at the "C". The actual Bradford Ridge Path (trail) is labeled on Google maps (north of the "C" if you zoom in a little). With this route you can drive on a paved road all the way to the trail, but if there is snow in Twin Peaks/Lake Arrowhead, you may need chains. While paved, the last 2 or 3 miles of this route are not well maintained.
Hope you make it and have a good time.
http://goo.gl/maps/ewXsJ