Install Scala on CentOS
Create a directory for scala under /usr/lib/scala. If you choose to use scala v2.10, you can put that inside this directory as well and use "alternatives" to switch between two versions.
Move the scala binary to /usr/lib/scala
Create a symlink to scala executable.
Make sure /usr/local/bin is in $PATH. You can update /etc/profile to set the PATH.