How do i define array in shader's constant buffer with C#?

I am using SharpDX to render 3D graphics and i cannot get to work constant buffer in my shader since it contains an array. Currently it looks like this:

cbuffer cb0 : register(b0)
{
    matrix mWorld;
    matrix mView;
    matrix mProj;
    float4 vLightDir[2];
    float4 vLightColor[2];
    float4 vOutputColor;
}

But how to define a struct in C#, which will be correctly marshalled to such constant buffer in shader? In C# we don't have "excplicit" array initialization, e.g. this line of code i used in C++ will not work in C#:

struct cb0
{
  // ...
  Vector4 twos[2];// C#: Vector4[] twos;
// ...
}

I always set StructLayout option Pack=16 for my structs for alignment, but HOW to define such struct with C#? i have tried to define struct like this:

struct cb0_t//pack=16
        {
            public Matrix mWorld;
            public Matrix mView;
            public Matrix mProj;
            public Vector4 vLightDir0;
            public Vector4 vLightDir1;
            public Vector4 vLightColor0;
            public Vector4 vLightColor1;
            public Vector4 vOutputColor;
        }

Yes, it works with this, but this IS NOT COOL. Thank you, sorry for my english...