its possible! and you don't need a shader. but you must have a unique Block texture.
try this:
Code:
int x = 1;
int y = 1;
var format;

BMAP* tex2 = bmap_create("neueTextur.bmp");
var format2 = bmap_lock(tex2,0);
var format = bmap_lock(bmap_for_texture("metalplain4"),0);
for(y = 0; y < bmap_height(tex2);y++)
{
	for(x = 0; x < bmap_width(tex2); x++)
	{				
		var format; var pixel;
		pixel = pixel_for_bmap(tex2,x,y);
		//pixel = pixel_for_vec(color,100,format);
		pixel_to_bmap(bmap_for_texture("metalplain4"),x,y,pixel);
	}
}
bmap_unlock(bmap_for_texture("metalplain4"));
bmap_unlock(tex2);


in this code "metalplain4" is the name of the texture.
"neueTextur.bmp" is the new texture file. you have to control the size of both textures, because the textures must have the same size!
i experimented with this feature some days ago and it is really cool!

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