I have got rs-w (version 1.0RC1) to work on the Mac using Wine!
You will need WineBottler and Wine and both can be obtained from
here (direct download link). You will also need XQuartz if you are running OS X Lion or above which can be obtained from
here (direct download link).
All the basic functions appear to work, but more time is needed to test the advanced functions.
For the skeptics, I have attached a screenshot or two to show that this works.
Thank you to Roseway for making the app in the first place.
Enjoy!