byob : BYOB (Build Your Own Blocks) is an advanced offshoot of Scratch ( http://snap.berkeley.edu/old-byob.html )
scratch : A programming environment for creating stories, animations, games, and music. ( http://scratch.mit.edu/ )
Add an ebuild in portage :
The ebuild is now in the portage tree.
You can also use layman : emerge layman then layman -a superposition
For Paludis use this rsync : rsync://gentoo.zugaina.org/superposition-portage
If you have a problem : ycarus(-at-)zugaina.org