my ~/.sbtconfig, works w/ SBT 0.13 and ansi-term

.sbtconfig

SBT_OPTS="-XX:+CMSClassUnloadingEnabled -XX:MaxPermSize=256m -Xmx512M -Xss2M"

# this allows sbt to be executed in Emacs terminal
if [[ -n $EMACS ]]; then
   echo "Emacs detected, commencing hijacking sequence..."

   # to avoid division by zero, with jline 1.0, see https://github.com/sbt/sbt/issues/714
   stty columns 80

   # avoid fancy colors that comint-mode won't support anyway
   #SBT_OPTS="$SBT_OPTS -Dsbt.log.noformat=true -Djline.terminal=jline.UnsupportedTerminal"

   exec rlwrap java -Xmx512M ${SBT_OPTS} -jar /usr/local/Cellar/sbt/0.13.0/libexec/sbt-launch.jar "$@"
fi