How to apply gradient texture in WorldSpace in CG shader

What I want to achieve is multiplying my first Pass (cg) by a second Pass which applies a gradient texture to the object, but which gets projected onto the object in (TexGen WorldSpace), so that it doesn't use the object's UVs...I guess maybe like a Toon Ramp if I'm correct?

I tried doing it in a second Pass, which was cg as well, but the (TexGen "") option for the 2D texture is disabled in custom vertex shaders. So do I need to write the second Pass in ShaderLab Fix Function Pipeline? And does the Ramp texture need to be a normal 2D map or a cubemap?

I hope someone can help me out because I'm a little stuck on this one lol

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EDIT: Posting shader source

I have my shader source code in a custom .cginc file (BraaapCG.cginc), but I would like to add the gradient in the actual shader file, and keep it out of the source code in the .cginc file:

 #pragma fragmentoption ARB_precision_hint_fastest
 #pragma exclude_renderers xbox360 ps3
 #define UNITY_PASS_FORWARDBASE
 #include "UnityCG.cginc"
 #include "Lighting.cginc"
 
 
 // ================================= Data structs for vertex and pixel shaders
 // Object data coming in
 struct appdata
 {
     float4 vertex : SV_POSITION;
     fixed3 normal : NORMAL;
     half2 texcoord : TEXCOORD0;
     half2 texcoord1 : TEXCOORD1;
 };
 
 // Vertex 2 Fragment data
 struct v2f
 {
     float4 pos : SV_POSITION;
     fixed4 color : COLOR;
     #ifdef DIFFUSEMAP_ON
     half2 uvMT : TEXCOORD0;
     #endif
     #ifdef DETAILMAP_ON
     half2 uvDT : TEXCOORD1;
     #endif
     #ifdef LIGHTMAP_OFF
     #ifdef VERTEX_LIT
     fixed3 normal : TEXCOORD2;
     fixed3 vlight : TEXCOORD3;
     #endif
     #else
     half2 uvLM : TEXCOORD2;
     #endif
 };
 
 
 // ================================= Properties used
 #ifdef COLOR_ON
 fixed4 _Color;
 #endif
 #ifdef DIFFUSEMAP_ON
 float4 _MainTex_ST;
 sampler2D _MainTex;
 #endif
 #ifdef DETAILMAP_ON
 float4 _DetailMap_ST;
 sampler2D _DetailMap;
 float _Blend;
 #endif
 #ifdef LIGHTMAP_ON
 float4 unity_LightmapST;
 sampler2D unity_Lightmap;
 #endif
 
 
 // ================================= Custom Functions
 #ifdef VERTEX_LIT
 // Half-Lambert Lighting (wrap-diffuse)
 inline fixed3 HalfLightingLambert ( fixed3 normal, fixed3 lightDir )
 {
     fixed NdotL = max ( 0, dot ( normalize( normal ), normalize( lightDir ))) * 0.5 + 0.5;
     return _LightColor0.rgb * ( NdotL * NdotL * NdotL ) + UNITY_LIGHTMODEL_AMBIENT;
 }
 #endif
 
 
 
 // ================================= VERTEX SHADER
 v2f vert ( appdata v )
 {
     v2f o;
     o.pos = mul( UNITY_MATRIX_MVP, v.vertex );
     
     #ifdef DIFFUSEMAP_ON
     o.uvMT = TRANSFORM_TEX( v.texcoord, _MainTex );
     #endif
     
     #ifdef DETAILMAP_ON
     o.uvDT = TRANSFORM_TEX( v.texcoord1, _DetailMap );
     #endif
     
     #ifdef VERTEX_LIT
     #ifdef LIGHTMAP_OFF
     o.normal = v.normal;
     fixed3 lightDir = ObjSpaceLightDir(v.vertex);
     o.vlight = HalfLightingLambert( o.normal, lightDir );
     #endif
     #endif
   
     #ifdef LIGHTMAP_ON
     o.uvLM.xy = v.texcoord1.xy * unity_LightmapST.xy + unity_LightmapST.zw;       
     #endif
     
     #ifdef COLOR_ON
     o.color = _Color;
     #endif
     
     return o; 
 }
 
 // ================================= PIXEL SHADER
 fixed4 frag( v2f i ) : COLOR
 { 
     fixed4 diff = i.color;
     
     #ifdef DIFFUSEMAP_ON
     diff = tex2D( _MainTex, i.uvMT );
     #ifdef COLOR_ON
     diff *= i.color;
     #endif
     #endif
     
     #ifdef DETAILMAP_ON
     fixed4 detail = tex2D( _DetailMap, i.uvDT );
     #ifndef DIFFUSEMAP_ON
     diff = detail;
     #ifdef COLOR_ON
     diff *= i.color;
     #endif
     #endif
     #endif
     
     #ifdef DIFFUSEMAP_ON
     #ifdef DETAILMAP_ON
     diff *= detail * _Blend;
     #endif
     #endif
     
     // Apply lighting
     #ifdef VERTEX_LIT
     #ifdef LIGHTMAP_OFF
     diff.rgb *= i.vlight * 2;
     #endif
     #endif
     
     // Or apply lightmap if turned on( with no lighting )
     #ifdef LIGHTMAP_ON
     diff.rgb *= DecodeLightmap( tex2D( unity_Lightmap, i.uvLM ) );
     #endif
  
     return diff;
 }

Then here's the actual shader:

 Shader "SRShaders/ColorOnly/Single_Color_VertexLit" {
 
 Properties {
 
     _Color ("Main Color", Color) = (1,1,1,1)
     _Ramp( "Ramp (RGB)", 2D ) = "grey" {TexGen EyeLinear}???
 }
 
 // Single Color shader, vertex lit w/lightmap
 SubShader {
     Pass 
     {
         Name "COLOR VERTEX LIT"
         Tags { "LightMode" = "ForwardBase" }
 
         
         CGPROGRAM
         #pragma vertex vert
         #pragma fragment frag
         #pragma multi_compile_fwdbase LIGHTMAP_OFF LIGHTMAP_ON
         
         #define COLOR_ON
         #define VERTEX_LIT
         #include "../BraaapCG.cginc"
         
         ENDCG
     }
     Pass
     {
         // Here I would like to add(multiply) the Ramp texture to the
         // previous pass, in WorldSpace (or any space that fits my purpose).
         // I want to do it this way so that the UVs of the object don't matter
         // for the _Ramp texture, that way it maps it vertically or horizontally
         // across the whole object
 
        //CG or Shaderlab code...
     }
 }
 }

I have read that the {TexGen ""} tags don't work in custom vertex shaders, so I'm assuming I'd need to use ShaderLab and SetTexture[_Texture]{...}, but I'm not sure how to make it work.

EDIT END =========================

Thanks in advance!
Stephane