The best way to do it, IMHO, is to enter from behind the temporary tattoo stand in Discovery Island (opposite the Baby Care Center). We spent almost an hour on that path the other day. We got great views of the tree, and also of the kangaroos and lemurs and I forget what else. The other end of the path is behind the ITTAB FP machines. We did the Wild by Design tour and that path was what the tour guide recommended as her favorite, and it was *so* worth it.
I can't tell on Robo's map, but I *think* the path he's marked is a different one and that the one I'm thinking of starts a bit below the one he's marked on the left hand side, then curves around and exits near the bottom. I'm pretty sure we did both paths separately and they didn't really overlap.
There's also a path marked "Photo Trail" as you come over the bridge onto Discovery Island.