Okay, so I've been playing with this for a while and I came to a reasonable solution since I don't have any programming skills...
This is one way you can get a song to play for an alarm instead of those f*ing beeps that it makes by default.
1.First, you need to make the Ipod think it's kind of like an iPhone. You could make it think it's an iPhone completely, but I've found that's just annoying unless you're insecure and want everyone to think you're way cool and have an iPhone. So first, you need to SSH into the iPod, and get at the Springboard N45AP.plist file, which is located in
/System/Library/CoreServices/SpringBoard.app
open that up in a Property List Editor (easier) or a text editor, and make it look like one of these two respectively.

(In a Property List Editor)
or

(In a text editor, or at least that's the only important part of it, the rest can remain as-is)
then, having SSHed into the iPod, create a folder in /Library called "Ringtones". I actually just copied the Ringtones folder from some iPhone firmware, but I think it will still work if you don't.
2. Find an mp3 or some audio you want to use, import it into iTunes if it's not already there
4. Select the file, click File>Get Info, then click Options, and adjust the start and end time to whatever bit of the audio you want to use.
3. Click Advanced>Convert Selection to AAC (if it says some other file format, go to iTunes Preferences and change the import format to AAC)
4. Find the converted file in the iTunes Library folder on your computer, and change the extension to .m4r instead of .m4a
5. Copy this file to the new "Ringtones" folder in your iPod
6. Respring or restart your iPod and you should be able to use the audio file as an alarm now.
NOTE: BACKUP YOUR N45AP.PLIST BEFORE YOU ALTER IT IN CASE SOMETHING GOES AWRY. I DOUBT IT WILL, BUT I CAN'T GUARANTEE ANYTHING. PERFORM AT YOUR OWN RISK. I TAKE NO RESPONSIBILITY FOR ANYTHING THAT HAPPENS TO YOUR DEVICE.
NEW NOTE: IF YOU MAKE AN ENTIRE TRACK INTO AN ALARM, IT TENDS TO TAKE UP MUCH OF THE MOBILE MEDIA SPACE, I.E. SPACE FOR THIRD PARTY APPS, ETC, (NOT MUSIC, PHOTOS OR VIDEOS)