Shader that blends more than 2 textures

Hi,

I need to create a shader that allows you to blend more than 2 textures. I started with this below.`

http://wiki.unity3d.com/index.php/Blend_2_Textures.

I've attempted to try to modify it to incorporate more that 2 textures. I was able to add a third but unfortunetly it will only blend the tex01 and 02 but not the third. I'm a new to writing shaders. Not sure what I did wrong here.

Here's what I modified.

 Shader "Blend 3 Textures" { 
 Properties {
     
 _Blend01 ("Blend01", Range (0, 1) ) = 0.5 
 _Blend02 ("Blend02", Range (0, 1) ) = 0.5
 _MainTex ("Texture 1", 2D) = "" 
 _Texture2 ("Texture 2", 2D) = ""
 _Texture3 ("Texture 2", 2D) = ""
 
 }
 
 SubShader {    
 Pass {
         
 SetTexture[_MainTex]
 SetTexture[_Texture2]
          
 { 
             
 ConstantColor (0,0,0, [_Blend01]) 
 Combine texture Lerp(constant) previous
 }    
         
 SetTexture[_Texture2]
 SetTexture[_Texture3]
         
 {
 ConstantColor (0,0,0, [_Blend02]) 
 Combine texture Lerp(constant) previous
             
 }
 
     }
 } 
 }
 

Any help would be greatly apperciated.

Thanks!