How do I downgrade Java on OSX 10.6.8?
If anyone still cares about downgrading Java on Snow Leopard, the answer that advises removing Java manually and reinstalling from download or Snow Leopard DVD doesn't work for Snow Leopard, but it can be made to work.

Instead of using the freestanding Java packages on the DVD, use the app Pacifist to open the main Snow Leopard installer .pkg. Then search for "java" and install every item that matches (you can skip the JavaScript items, obviously). This fixes the error reported in the linked article (which is offline but available at archive.org):

"Error occurred during initialization of VM
Unable to load native library: libjava.jnilib"

Apparently there are additional pieces to a functioning Java install not included in the separate .pkg files.