How to write Diffuse shader with Pass{} instead of surface?

Hello guys,

Sorry for my question, im newbie with shaders.

I need two Pass{} in Diffuse shader for two faces - front and back (Using Cull Front and Cull Back, what is impossible to change with surface).
In some cases I wanna make back face semi-transparent and front face transparent.
So… How to transform “surface-based” shader into “Pass{}-based”?

TY for help

You can set Cull Front and Cull Back using surface shaders…

Shader "Custom/DoubleSided" {
Properties {
_MainTex ("Base (RGB)", 2D) = "white" {}
}
SubShader {
Tags { "RenderType"="Opaque" }
LOD 200
 
// Render back faces first
Cull Front
CGPROGRAM
#pragma surface surf Lambert vertex:vert
 
sampler2D _MainTex;
 
struct Input {
float2 uv_MainTex;
};
 
// Flip normal for back faces
void vert (inout appdata_full v) {
v.normal *= -1;
}
 
// Red back faces
void surf (Input IN, inout SurfaceOutput o) {
half4 c = tex2D (_MainTex, IN.uv_MainTex);
o.Albedo = fixed3(1,0,0);
o.Alpha = c.a;
}
ENDCG
 
// Now render front faces
Cull Back
CGPROGRAM
#pragma surface surf Lambert
 
sampler2D _MainTex;
 
struct Input {
float2 uv_MainTex;
};
 
// Green front faces
void surf (Input IN, inout SurfaceOutput o) {
half4 c = tex2D (_MainTex, IN.uv_MainTex);
o.Albedo = fixed3(0,1,0);
o.Alpha = c.a;
}
ENDCG
 
 
}
FallBack "Diffuse"
}