Change light direction in SS

Unity Engine
1

I am trying to make a Surface shader that uses a directional light with it’s lightDir angle xyz properties defined from the shader properties as a Vector property rather than using the main directional light in the scene. The reason for this is I want the shadows to derive from the scene’s main directional light, but the actual light applied to be coming from a different custom angle. Is this possible? What I am having initial difficulty on is figuring out how to convert my customLightAngle vector into the correct object/ world space so I can pass it into the surface shader. Thanks for any pointers.

vec ("customLightAngle", Vector) = (45,45,45,1)


fixed4 CustomLight (SurfaceOutputCustom s, fixed3 lightDir, fixed atten)
{	
	lightDir = myCustomVector;
	fixed diff = max (0, dot (s.Normal, lightDir.xyz )); 
}
2

Here is what I have so far. Still can’t figure out how to correctly turn a property vector into a directional light with rotation defined by the vector’s xyz.

  Shader "CustomVectorLight" {
    Properties {
	  lightDirVec ("light vec", Vector) = (45,45,45,1)       
    }
    SubShader { 
     Tags { "RenderType" = "Opaque" }
    
      CGPROGRAM 
#pragma surface surf CustomLight vertex:vert target 2.0  
    struct SurfaceOutputCustom {
	fixed3 Albedo;
	fixed3 Normal;
	fixed3 Emission;
	half Specular;
	fixed Gloss;
	fixed Alpha;
	fixed3 CustomLightDir;
};
    float3 lightDirVec;
fixed4 LightingCustomLight(SurfaceOutputCustom s, fixed3 lightDir, fixed atten)
{
	fixed4 c;
	c.rgb = max (0, dot (s.Normal, s.CustomLightDir.xyz )); 
	c.a = 1;
	return c;
}
    
      struct Input {
      float2 uv_Tex1;
	  float3 lightDirVec;  
      };
      
void vert (inout appdata_full v, out Input o) {
float3 objSpaceLightPos = mul(_World2Object, float4 (lightDirVec,1)).xyz;
objSpaceLightPos = objSpaceLightPos.xyz * unity_Scale.w - v.vertex.xyz;
TANGENT_SPACE_ROTATION;
o.lightDirVec = mul (rotation, objSpaceLightPos);
      }

void surf (Input IN, inout SurfaceOutputCustom o) {
      o.CustomLightDir = IN.lightDirVec.xyz;
      o.Albedo = .5f;    
      } 
      ENDCG
    }   
  }