This is how the tint color is declared in the skybox shader :

Properties {
    _Tint ("Tint Color", Color) = (.5, .5, .5, .5)
    // other stuff
}

Unfortunately, material.color is a property declared like that in Unity (because _Color is usually the name you give to the main color) :

public Color color{
    get{ return GetColor( "_Color" );
    set{ SetColor( "_Color", value );
}

This, with the fact that you can only assign a complete color to the property and not modify r,g,b, or alone, is why your code isn't working. Finally, Color's values are between 0 and 1, not 0 and 255. Here is the solution : (js)

skyBoxName.SetColor( "_Tint", Color( 0.0, 30.0 / 255.0, 0.0, 1.0 ) );

skyBoxName.color = Color( red, green, blue )

You can't directly set the r,g,b values, they're just for reading.