You need to make your own shader file, and set some shader flags. It's a little tricky to do at the moment, and it doesn't look as good as hand doing them, like you have.
If you want to try it, use a shader like this:
ps.1.4
def c0, 0.30f, 0.59f, 0.11f, 1.0f
texld r0, t0
dp3 r0, r0, c0(call it black_and_white.pp or something, and place this in your root m&B dir, with the other 2 shader files)
Then open up shaders.brf, and select any shaders you want to make black and white.
change file to black_and_white.pp
change flags to 268435456
change requires to 4096
then click the set button
If you change this for all the main shaders: tex_mul_factor, tex_mul_color etc, you end up with something like this:
Like I said though, if you manually do it, you can add a lot more style to the textures, but the upside of this approach is that all you need to upload is about 2kb: the shader.brf, and the shader pp file. Also it will work for all mods, with whatever custom textures they have. Oh and another advantage of doing it in shaders is that you shouldn't get the green areas in the ground on battle maps etc.
You could always just stylise the main textures, and black&white the rest... not trying to discourage you or anything, I think it looks pretty cool already
