I also can't get shaders to work. Here is what I'm using.
OptiFine_1.5.2_HD_U_D5 (OptiFine_1.5.2_HD_U_D3)* Make sure its D3 or same ver. the shaders mod.
ShadersMod-mc1.5.2-ofud3-1.46
I extracted these in the above order to minecraft.jar (modpack.jar)* located in (.technic/hexxit/bin).
Working in all its shady goodness.