For Windows Users

This a bit theoretical (untested, please correct me if I am wrong)

You should have regular (vanilla) processing installed, and probably cygwin installed.

At a minimum you will need to java installed (preferably latest stable version), you cannot rely on the version included with processing. You will also need a version of ruby installed, preferably latest stable version or jruby-1.7.25, which you can get here windows installer. You can get by with just a regular ruby installation, but you would need to set config to JRUBY = 'false' or alternatively use the --nojruby option on all sketches.

###Configuration### In addition to setting the processing root (if you follow PhiLhos lead this could be c:/Java/Processing-2.2.1, note no stupid folder names with spaces or other daft/illegal characters) it may also be necessary to set the path to ruby-processing root RP5_HOME in the .rp5rc file ( because of lack of relative path support? ). The post installer uses wget to download rp5 setup install, however if you haven't got wget, you can manually download jruby-complete and put in the the vendors folder and re-run rp5 setup install