The First Junction
Follow the trail from the parking lot for about 1/4 mile until you hit the first spur on the right which is now marked as "Boulder Garden Loop Trail". Turn right and follow this past some giant mossy boulders. From that first junction, continue for another half mile to another junction. Take a sharp right leaving the Boulder Garden trail. You will knoe it's the right trail if it begins with a couple of big stone steps. Thankfully this trail is not nearly as crowded as the new trail and there are far less switchbacks as well. Eventually this way joins up with the regular trail about 1/5 mile from the top. On your way down make sure you know the turn off to get to the old trail or you will have a long trek back to your car from the other trailhead.
The Second Junction
From Seattle take I-90 East to Exit 32. Turn left at the Stop, continue for 0.6 mile to next Stop and turn left and then a very immediate right between an Espresso Stand and a Motel. After .2 miles you will cross a bridge. Immediately after the bridge, the road will curve to the right and the new trailhead will be clearly visible on the left marked "Little Si".
Winter time - Instep crampons and poles are needed. An ice axe is needed if you plan on climbing the haystack in the winter.