This is a thing we use here at VictorOps, and it's awesome.
$ git clone https://github.com/victorops/akka-console-example.git
In terminal one:
$ cd akka-console-example
$ sbt counter/run
In terminal two:
$ cd akka-console-example
$ sbt console/run
In the ammonite REPL:
@ getCount
@ incrementCount
@ resetCount