Step 1. Locating your UT2004 directory

Your UT2004 directory is found by entering your hard disk C: and clicking the UT2004 folder. Simple huh?

Step 2. Where the Files go

If the model is a .zip, most readme's will tell you to extract the files from the zip to the folders. But I'm more partial to extracting the files to a new folder. So below is how to manually install the files.

Note: The name of the folder is in quotation marks.

.UTX files go in the "Textures" folder
.UKX files go in the "Animations" folder
.UAX files go into the "Sounds" folder
.KA files go in the "Karmadata" folder
.UPL files go in the "System" folder
.U files go in the "System" folder

Note: If the file downloaded includes a file in a "UMOD" format (.UMOD or .UT4MOD) then the files will be installed automatically.

That is it for installing but skip down to step three if you are having problems.

Step 3. Troubleshooting

If your Model is not working it is probably because the files were not installed correctly.
Make sure files are in the correct folders. The biggest cause for this one is using the extracting method, which is why I used a different one.
Also if you had a UMOD it may not have installed the file correctly. ALWAYS download a zip if given the option between the two.

Happy Fragging!