As we get more mirrors I'll post the links, also be sure to check out the docs here (the docs are also installed with the mod to Neotokyo/Help).
Neotokyo Public Alpha 0.21 Mirrors:
Download
Neotokyo Public Alpha 0.21 Zip for Linux/Mac
Download
Unzip to your root UT2004 Directory.
A massive thanks to those who have mirrored this for us :)