These instructions replace the default OS X cursor with an empty image. This can be helpful for full-screen environments, where the cursor cannot be set from within the application.

Open the Terminal (Applications -> Utilities -> Terminal) and type the following commands:

• Make a copy of the existing arrow cursor:

cp /System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/HIServices.framework/Versions/A/Resources/cursors/arrow/cursor.png /tmp
open -A Preview /tmp/cursor.png

• Clear and save the image (e.g: ⌘ + a, Fn+delete, ⌘ + s)
• Replace the arrow cursor image with the empty image

sudo cp /tmp/cursor.png /System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/HIServices.framework/Versions/A/Resources/cursors/arrow/cursor.png

• Restart your box