Well, don't get your hopes up too high - it only takes a few minutes to get through it!
From the MacNamara parking lot, head North towards the Riverbend parking lot, following the trail to the right around the pond near the lot. Follow that trail for ten minutes, staying on the main path and not getting off. Eventually you will go through a field, climbing up in it, then going downhill in it. At the bottom you will cross a nice new wooden bridge about 8 feet wide and 20 feet long, going over a 5-foot wide creek. Keep going another 30 yards and on the left of the main path you will see the new trail entrance. Note that it is not the first left, which is only 5 or 10 yards after the bridge (I think it has a sign saying Yellow cut-off among other things).
From the Riverbend lot, it's a bit more difficult to explain. But I will try anyway! Head in to the trails and turn left (South) at the river. Don't take the first two rights (second one is Swamp Thing and I think it is still closed). Keep going and don't turn off and you will get to the river. Head left (South) and you will reach the intersection where this new trail exits. It is an intersection near the river with a couple of crossing trails and a sign, and the entrance to Dragonball Run is beside the river there. Don't ride the new trail backwards - to get to the entrance of the new trail, either take Dragonball Run South or take the beginner trail South alongside Dragonball. Eventually you will reach an intersection where you can go right down a dip and over a bridge BUT keep going straight at that point and follow it as it curves left and goes alongside the creek (this might be the Yellow cut-off, I'm not certain). When you get to a T intersection, the bridge I mentioned above will be a few yards to your right. Turn left back towards the Riverbend lot and the new trail entrance will be on your left about 20 yards along the main trail.
Hope this helps ...