Place the contents of the .etwolf-player folder in your Enemy Territory installation folder. The configuration will be automatically loaded the next time you start the game. To reload the configuration while playing, press F8. You should receive notifications in the pop-up area to confirm that the configurations have been loaded. To apply any graphics changes which require a vid_restart, press N.
Configuration benchmark
The following graph shows the relative difference in frame-rates between the 3 default configurations and this one.