Sprite/Vertext Colored, Fast Shader - Black and White

I'm not familiar with cusomizing shaders. Does anyone know how to make a Sprite/Vertex Colored Fast shader Black and White?

Here is the default shader:

 Shader "Sprite/Vertex Colored, Fast" {
 Properties {
     _MainTex ("Particle Texture", 2D) = "white" {}
 }
 
 Category {
     Tags { "Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent" }
     Blend SrcAlpha OneMinusSrcAlpha
     Cull Off Lighting Off ZWrite Off Fog { Color (0,0,0,0) }
     
     BindChannels {
         Bind "Color", color
         Bind "Vertex", vertex
         Bind "TexCoord", texcoord
     }
     
     SubShader {
         Pass {
             SetTexture [_MainTex] {
                 combine texture * primary
             }
         }
     }
 }
 }