Not sure if there already is tutorial but heres a video tutorial.
ermm not sure how upload but im trying will be uploaded within the next hour.
Sorry.
cant get the video so heres a step by step in words....



First right click toribash go to open file location go to data....shader..... <.< (thats a list of shader names)
minimize that open toribash go to single player type /lws (shader name here).inc

There u go.

Ps,
If anyone can tell me how to upload a video id be happy to upload video.

Just upload it in youtube and paste it here.

generally if you cant get shaders from the in-game menu you wont get them at all.