Cromwell is a replacement BIOS for the xbox, which means there are two ways to run it. You can run it on a modchip, because xbox modchips simply override the Microsoft BIOS, or you can flash Cromwell to the system's TSOP itself on
version 1.0 - 1.5 consoles. 1.6 consoles have ROM instead of TSOP.
Keep in mind that Cromwell is incapable of running games (signed code) at all, even legitimate ones. It was developed specifically as an alternative OS loader and attempts to deter piracy.
Another option is Xromwell. I've not personally used it, but it's Cromwell in the form of an XBE you can launch from your homebrew dashboard of choice. The softmod method is very easy to set up. Search the Internet for "NDURE", my mod of choice. This option is somewhat less lawful, because a softmodded xbox is capable of playing copied game discs, and the vast majority of homebrew is compiled with a stolen XDK.
Regardless, performing the softmod is as simple as:
- Transferring a special game save file to your console with an Action Replay or via another modified console
- Running one of three vulnerable games. I use Splinter Cell.
- Installing NDURE with the options you choose
After that, you should have a functioning FTPd on the console and the ability to run unsigned code.
Be warned, the hard drive in the xbox is very small, usually 8GB. It's possible to replace the hard drive with a much larger one by the softmod or modchip methods, though softmod users must re-lock the new drive with the console's identifier. The xbox is actually the only time I've ever seen
ATA security in use.
For another suggestion, xbox consoles make very nice media centers using XBMC, though they are not powerful enough to play HD content.