Well, its a new forum, so I'll post them again here.
Disclaimer:
-All versions use a directory "hack" to allow for the binary and dlls to be placed in a subdirectory (more on this in the how to install section).
-The SDL build uses a non-release DLL since it is required for x64 purposes.
-This is currentently considered unofficial, but should work fine, the only change to the code from the 1.5 release is the earlier mentioned directory hack.
So how to install?
Extract THIS package into your Nexuiz directory. It should add a directory called "engin64" The reason for this is so that you can still have 32bit binaries as well.
The 32bit versions will be located in your Nexuiz\ directory.
The 64bit versions will be located in your Nexuiz\engine64 directory.
The 64bit versions all have "64" in the filename for clarification.
So just make sure you are not overwriting your 32bit files and that a subfolder is being made and you should be good to go, just launch the 64bit executable from your Nexuiz\engine64 directory!
Any problems, please post here and I'll address them as best I can.
Once again, the download is:
http://willis.planetnexuiz.com/nex64/nexuiz_win_x64_v15.zip