From the Mission, corner of Laguna and Los Olivos Street in Santa Barbara...
Get on US 101 going northbound by taking Laguna St. to Mission St. (toward the ocean).
Turn right on Mission St.
Follow Mission St. to the freeway and take US 101 north.
Take the Lake Cachuma/Highway 154 exit. Follow signs to Highway 154 and turn right on to 154.
Head up the mountains and down the other side.
As you see Cachuma Lake on your right, stay on the lookout for your turnoff, which will be on your left. You are looking for signs that say Camp Whittier, St. Vincent de Pauls Circle V camp and Camp Allegre. There is a very prominent sign for Camp Allegre, which is a Boy Scout camp, that you will see, but don't turn there. You want the next turn off, which also has a Camp Allegre sign, but much smaller. You should probably see the Camp Whittier sign there with it.
Just as you turn left here from 154 you see two ways you can go. Take the left. It should be marked with a Circle V sign (like a branding iron symbol.) You are going to be parking at the Circle V camp, which is the St. Vincent de Paul's camp.
Don't take any of the turns on this horribly pot-holed, dusty road. Just stay on it all the way to the end, where there is a little parking area on the right where you should park, and a gate on the left, where the camp is and also where the trailhead is.
Park in the parking lot. You don't need an Adventure Pass to park your car. The hike begins at the gate. You will be walking through the camp.