Recieving Shadow on Custom Shader

Basically I’ve got this custom shader for silhouette highlight from Unity3d Wiki… (I Know nothing about Shaders… purely programming background). I want this Shader to recieve shadow casted by other objects

Shader code:

Shader "Outlined/Silhouetted Diffuse" {
	Properties{
		_Color("Main Color", Color) = (.5,.5,.5,1)
		_OutlineColor("Outline Color", Color) = (0,0,0,1)
		_Outline("Outline width", Range(0.0, 0.03)) = .005
		_MainTex("Base (RGB)", 2D) = "white" { }
	}

		CGINCLUDE 
#include "UnityCG.cginc"

	struct appdata {
		float4 vertex : POSITION;
		float3 normal : NORMAL;
	};

	struct v2f {
		float4 pos : POSITION;
		float4 color : COLOR;
	};

	uniform float _Outline;
	uniform float4 _OutlineColor;

	v2f vert(appdata v) {
		// just make a copy of incoming vertex data but scaled according to normal direction
		v2f o;
		o.pos = UnityObjectToClipPos(v.vertex);

		float3 norm = mul((float3x3)UNITY_MATRIX_IT_MV, v.normal);
		float2 offset = TransformViewToProjection(norm.xy);

		o.pos.xy += offset * o.pos.z * _Outline;
		o.color = _OutlineColor;
		return o;
	}
	ENDCG

		SubShader{
		Tags{ "Queue" = "Transparent" }

		// note that a vertex shader is specified here but its using the one above
		Pass{
		Name "OUTLINE"
		Tags{ "LightMode" = "Always" }
		Cull Off
		ZWrite Off
		ZTest Always
		ColorMask RGB // alpha not used

					  // you can choose what kind of blending mode you want for the outline
		Blend SrcAlpha OneMinusSrcAlpha // Normal
										//Blend One One // Additive
										//Blend One OneMinusDstColor // Soft Additive
										//Blend DstColor Zero // Multiplicative
										//Blend DstColor SrcColor // 2x Multiplicative

		CGPROGRAM
#pragma vertex vert
#pragma fragment frag

		half4 frag(v2f i) :COLOR{
		return i.color;
	}
		ENDCG
	}

		Pass{
		Name "BASE"
		ZWrite On
		ZTest LEqual
		Blend SrcAlpha OneMinusSrcAlpha
		Material{
		Diffuse[_Color]
		Ambient[_Color]
	}
		Lighting On
		SetTexture[_MainTex]{
		ConstantColor[_Color]
		Combine texture * constant
	}
		SetTexture[_MainTex]{
		Combine previous * primary DOUBLE
	}
	}
	}

		SubShader{
		Tags{ "Queue" = "Transparent" }

		Pass{
		Name "OUTLINE"
		Tags{ "LightMode" = "Always" }
		Cull Front
		ZWrite Off
		ZTest Always
		ColorMask RGB

		// you can choose what kind of blending mode you want for the outline
		Blend SrcAlpha OneMinusSrcAlpha // Normal
										//Blend One One // Additive
										//Blend One OneMinusDstColor // Soft Additive
										//Blend DstColor Zero // Multiplicative
										//Blend DstColor SrcColor // 2x Multiplicative

		CGPROGRAM
#pragma vertex vert
#pragma exclude_renderers gles xbox360 ps3
		ENDCG
		SetTexture[_MainTex]{ combine primary }
	}

		Pass{
		Name "BASE"
		ZWrite On
		ZTest LEqual
		Blend SrcAlpha OneMinusSrcAlpha
		Material{
		Diffuse[_Color]
		Ambient[_Color]
	}
		Lighting On
		SetTexture[_MainTex]{
		ConstantColor[_Color]
		Combine texture * constant
	}
		SetTexture[_MainTex]{
		Combine previous * primary DOUBLE
	}
	}
	}

		Fallback "Diffuse"
}

Basically; you can’t. The shader relies on the transparent render queue (I’m assuming from the code) and there is no way in Unity (currently) to render shadows on transparent objects without creating your own lighting/shadow system, or essentially hacks. I did develop a transparent shader to receive shadows from Unity lights, but it’s somewhat impractical and unreliable. Transparent shadow receivers have been on the Unity roadmap for a while now, and I believe were supposed to be brought in by Unity 5, but that didn’t happen.