Another way to create banyan roots (Which are atually roots that originate from branches ) whould be to use the naturaly ability fo plants to create air roots. The technique posted earlier will give the illusion of air roots. However, they are just a showing off of washed-away soil around the normal roots. It may look nice, but they are not true air-roots.
Schefflera is capable of creating air-roots of its own. All that is needed are suitable conditions. Note however that most plants will only create these roots when they are somewhat older. One species especially good at creating air roots is ficus. I have a ficus Elastica that has over 15 1/2 inch thick air roots from all over the plant. Main thing: Make sure the plant is moist often; For Schefflera I think you can stimulate air-roots by spraying often, and e.g., slightly damaging (trimming) the normal roots in the warm growing season. This way the plant will try to create assistence to the original roots.
In my case, the ficus i have started with tiny little roots on the stem. When I started misting these for a few weeks, the started growing down like crazy. Make sure you train the roots to the right spot in the soil or you'll get a mess around the plant (Sigh, I know I should have organized them).