Daren Thomas started a GitBook to describe how RevitPythonShell and Revit interact, and perhaps you may find something useful that could assist with creating custom Python nodes for Dynamo…
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Scripting Autodesk Revit with RevitPythonShell – GitBook
Something else that should be mentioned. If for some crazy reason you don't want to install the truly wonderful RevitPythonShell plugin, ever since Revit 2014, the built-in macro editor has had support for python and ruby.