Scala tools gentoo overlay
Contains scala-related ebuilds.
Using Layman
This overlay can be integrated into your system using layman (http://wiki.gentoo.org/wiki/Layman).
$ sudo layman -f --overlays https://github.com/whiter4bbit/overlays/raw/master/layman.xml --add gentoo-scala-tools
$ sudo emerge sbt-bin # to emerge sbt
Using eselect-scala
You can have multiple installed scala versions and select active using eselect:
$ sudo emerge eselect-scala
$ sudo eselect scala list
$ [1] scala-2.9.0 *
$ [2] scala-2.8.1
$ sudo eselect scala set scala-2.8.1
$ scala-2.8.1