1) Put all the downloaded .rar files in your Fallout:New Vegas 'root'* directory.


64 bit: "C":Program Files (x86)SteamsteamappscommonNewVegas

32 bit: "C":Program FilesSteamsteamappscommonNewVegas
....or the custom location you installed the game.
Note: Where the "C" is could be any letter it is commonly C, but can be other letters too.

2) Unpack the FIRST ONLY .RAR file. The other .RAR files will automatically unpacked if they are present in the same folder, so DON'T extract those seperately.

2a) DOWNLOAD AND INSTALL THE PATCH!

3) IMPORTANT: Activate "archive invalidation invalidated" so the new files show up in game. (Also, if you are overwriting a previously installed, different sized pack, THEN TOGGLE ARCHIVE INVALIDATION INVALIDATED OFF, THEN BACK ON AGAIN or the new textures may not show up)
You can activate this in the Fallout Mod Manager Mod (FOMM)
or by using the Archive Invalidation Invalidated mod.

4) Due to the size and number of files your poor PC now has to process, you should make New Vegas 'Large Address Aware' (ie. let it use more than 2GB, which it is currently locked to) to give New Vegas more memory access. This can reduce crashing and even give a performance/ framerate boost! Your mileage may vary.