So maybe you should try another installation. The manual installation is very easy. I assume that you already have Ruby (maybe it's preinstalled, otherwise you have to install it). You can check if you have Ruby by opening a terminal/console window and typing `irb`. If you see a Ruby prompt then you have Ruby, otherwise you have to install it first.
Locomotive development has come to an end. With the advent of a fully-functional Ruby and Rails stack on Leopard, Locomotive is no longer needed. Also, I don't have the time anymore. Thanks for using it.