GLSL custom vertex attributes

Sorry for the newbie question but I’m not able to find out a solution …
How (if it’s possible at all) should I pass custom vertex attributes to a GLSL vertex shader that I link into my BGE scene with the common python code?

Thank you.

Sorry to bump this old thread. I suppose this is limitation of BGE. You can only pass tangent attribute, not else.

Maybe anyone know something about this?