I came across this project on InventGeek:

And I figured I could take it a step further by setting up a computer running StepMania inside the platform itself, creating a self-sufficient DDR-style gaming system.

But here's the problem. I haven't started building it yet, because I'd like to know that I can make the software work, so I'm experimenting on my personal system. Right now I've got a dual-boot set up between PCLinuxOS and Windows (for a few proprietary apps)

If I log into the console, I can simply type:
startx /stepmania-3.9/stepmania
...and X will start, immediately run the application, and terminate once I exit stepmania.

However, in order to access the console in the first place, I have to interrupt the bootloader and then login to the console under root.

How can I get the computer to run that simple command directly while booting?

Basically, the same way an ATM, or an arcade game would work. Turn the thing on, and X starts up and immediately runs the one and only application you want it to access?

Thanks in advance!