Unpack the .rar into C:Documents and SettingsusernameMy DocumentsMy GamesUnreal Tournament 3 and override folders if asked to.
Start UT3 and select Snowreal as gametype.
Select one of the Snowreal maps (at bottom of list) and you're ready to go!
* Don't set your Post Processing to Intense, as the snow will be blinding you way too much.
* Please set the World Detail to something higher than 1 as this might also render the snowreal maps super-bright.