You can see the tree house in most of the concept art for Equatorial Africa, as well as on the layout for the proposed pavilion (at the upper left below):
The attraction has been described
HERE (which also contains lots of concept art) as follows:
"At the entrance of the land, surrounded by huge Kopjis rocks, guests would have start their "Africa" experience with a giant 60 foot tall tree house. Up in the tree house a wooden observation platform, which surrounded the upper trunk. From the center of it thanks to WDI Imagineers wizardry and a real movie filmed by cinematographer Jack Couffer guests would have overlook a waterhole at dusk with wild animals of the jungle coming to bathe or drink. It would have been a multi senses experience as, in addition to the far projected 70 mm live action movie projected on a 20 foot screen, was included wind and heat effects as well as scents - thanks to Disney's "smellizer" technology - and HD sound to create the perfect illusion that guests were actually in Africa watching real wild animals."