What do you mean "it didn't seem to work"? Could you FTP to the Xbox? Could you see any of the drives? Could you copy a file from the Xbox to your PC? Could you copy a file from the PC to your Xbox?
Are you sure you are using an X3? Do you know which BIOS you are using? If you are using an X3 BIOS then just press and hold the white button on your controller while booting, and that will bring up X3 config live, which also has an FTP server built-in.
If you aren't using an X3 BIOS then you need to flash one to the chip. Boot by pressing power + eject at the same time, the X3 control panel LED will turn purple, and Flashbios will load. Follow these instructions
to load X3.3294 to banks 1,2,3 and 4, then reboot and press the white button to load X3 config live. Follow these instructions
to set up your Xbox to boot from C:\evoxdash.xbe as its first dash.
Once you've done that you can use HeXEn to rebuild your hard drive from scratch
- but note that this will delete your existing data on your Xbox. If you want to retain your existing data then the process is a bit more manual.