Unzip and copy the USERDATA.JAM on a USB stick, put it into your PS3, start UT3 and import the mod
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.