To run Verilog code directly, you need a Verilog simulator. Several open-source Verilog simulators are available that are compatible with the explicit-style output of VITO:
http://www.veripool.org/wiki/verilator
http://verilog2cpp.sourceforge.net/
http://sourceforge.net/projects/veriwell/
To the best of our knowledge, only one of these (veriwell) is also compatible with the implicit-style input to VITO. In other words, a good development environment for implicit-style state machines starts with Verilog source running on veriwell. When this source is debugged, VITO can then convert it to explicit-style, which can be simulated or synthesized by most tools.