The current (v8.9) facilities for Scilla/EVM interwork are fairly primitive; just enough to build the ERC20 -> ZRC2 gateway contract you can find in the zilliqa-developer repository. We hope to improve on these in future versions.
They consist of precompiles to call Scilla from EVM (either replacing
or retaining the
sender), and a precompile to read a fairly
restricted subset of Scilla state from EVM.
This documentation is being prepared - please check back in a couple of days.