I've changed my cursors under OS X for a long time now. Check out /System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/HiServices.framework/Versions/A/Resources/cursors for the special ones. (People make replacement packs that are drop-in replacements for the cursor image files.)
For the main cursor, use a combination of Cursorcerer and HotMouse.
For the main cursor, use a combination of Cursorcerer and HotMouse.