Just discovered: if you want to add this to faqs or the callum's post, be my guests

Editing .sgr files in TSDAta, on Macintosh, don't works: you have to edit the files inside the application BodyShop itself. That's because on Mac OS, all the applications are special folders, usually with all the most important data and settings in it.

Here's how to open that "folder" end edit the data inside:

1) Ctrl-click on BodyShop
2) Choose "Show Package Content"
3) Go to Body Shop.app/Contents/Resources/Config
4) Open Graphics Rules.sgr with TextEdit or other text editor
5) Edit according callum91 suggestions
6) Save and close Body Shop.app folder

That's it