Julian, I'm working in the same project as you! I sent an e-mail to Chriss some weeks ago and, from my understanding it is just a case o to get an Tennesy 4.1, rewire the limit switchs and motors, dir and pul forgetting the encoders. So, you could run the AR4 software even without enoders. When you turn on the software you need to uncheck the encoders to leave the robot in open loop. I have already bought the Tennesy and will be tring this in the next days.