If you are using conditional directives in your C# code, you know that you can't set a breakpoint on any code within the directives using Visual Studio. Thankfully, you can add a breakpoint programmatically:

#if MYSYMBOL
   #if DEBUG
      System.Diagnostics.Debugger.Break();
   #endif
   DoSomethingForMySymbol();
#else   
   #if DEBUG
      System.Diagnostics.Debugger.Break();
   #endif
   DoSomethingForEverythingElse();
#endif

System.Diagnostics.Debugger.Break() can only be called in Debug mode, so make sure you wrap it in a #if DEBUG check first. Good luck!