Install 'otls' into $HOME/Library/Preferences/houdini/{version} (or $HOME/houdini{version} on windows)
You can also copy the 'glsl' directory to the same location as 'otls', but you need to change the prog file path of the materials in the hip.
Please note that the 'glsl_shader_validator' operator requires a C++ compiler to work.
Only tested on my mac.