I faced the same problem, and using the mentioned installer didn't solve the problem for me.
This worked for me:
[*]Download the scala library file from here:
http://files.minecraftforge.net/maven/org/scala-lang/scala-library/2.10.2/scala-library-2.10.2.jar
[*]Download the scala compiler from here:
http://files.minecraftforge.net/maven/org/scala-lang/scala-compiler/2.10.2/scala-compiler-2.10.2.jar
[*]Put scala-library-2.10.2.jar into the folder .minecraft\libraries\org\scala-lang\scala-library\2.10.2\
[*]Put scala-compiler-2.10.2.jar into the folder .minecraft\libraries\org\scala-lang\scala-compiler\2.10.2\
[*]Now run the installer that luacs1998 posted and the installation should work as intended
