The only one I've ever heard of required installing a panel of colored (in this case, black) glass inside the tank. They put it in lengthwise and at an angle. Forgive the bad ASCII and ignore the ` marks, but this is sort of what it looked like in a side-view.
` ______
_|_____ \__
|`````````|
|...```````|
|...\ ~~~~|
|___\_____|
It was sealed in with aquarium putty on the sides and at the bottom seam. They filled the back with soil and sand and planted arrow heads and some small tropicals they bought at Wal-Mart. They decorated with rocks and driftwood. The front they gave a dark sand bottom and added silk plants, a submersible filter, and some decorative rocks like the ones used on the soil side.
It wasn't very pretty, but he used aquarium sealant and black sand to add texture to the angled glass so the critters could crawl in and out. In the end, it wasn't noticeable enough to be intrusive and I imagine you could glue layers of sand and rock and cover the whole glass making an interesting backdrop.
He used it for salamanders and briefly for a terrapin of some sort before someone offered him $250 for it and he sold it.