Installation : 
1-Be sure to have the latest graphics driver for your graphic card !
2-Download the specified optifine version (If you want to use forge, you need forge #673 for 1.5.2, forge #518 for 1.4.7)
3-Place optifine stuff into your minecraft.jar
4-Place the content of the shadermod folder for your version into your minecraft.jar
5-Open minecraft, options/shader/open shaderpack folder, place the "v3-lite","v3-low"...etc here.
6-Select my shaders, load a world, enjoy!