There is no squeak64 ebuild and simple squeak doesn't compile and is masked.
Steps to Reproduce:
1. emerge squeak
2. emerge squeak64
seems this request hasn't turned into an ebuild yet. If you want to help with it, it's not that hard to write one: http://devmanual.gentoo.org/quickstart/index.html
If you need further help, feel free to ask on forums or #gentoo-dev-help or #gentoo-sunrise on irc (latter is also useful if you want to maintain the app yourself)
note: we're not turning you down for this request in any way, it's just that we don't have ressources to fix all of them. though if you're willing to help, it would be more than nice to do so, as that is what we definately need :)