Question Control Passes by keywords?

I'm trying to make a replacement shader thats using UsePass function, but I need to select which pass to use by material, for example if the material Have certain keyword, use all passes, if don't have use only shadow caster pass.

Code (CSharp):

1.  
2.     SubShader
3.    {
4.        Tags { "RenderType"="Opaque" }
5.    LOD 0
6.  
7.        Cull Off
8.        CGINCLUDE
9.        #pragma target 5.0
10.        #pragma multi_compile __ _SHADERTYPE_BODY_ON
11.        ENDCG
12.      
13.        #ifdef _SHADERTYPE_BODY_ON
14.  
15.        UsePass "Myshader/LightingPassNode/FORWARDBASE"
16.        UsePass "Myshader/LightingPassNode/FORWARDADD"
17.        UsePass "Myshader/LightingPassNode/SHADOWCASTER"
18.        #else
19.        UsePass "Myshader/LightingPassNode/SHADOWCASTER"
20.  
21.        #endif
22.  
23.    }
24.  

But using ifdef condition failed to compile. How I can work around this?