TinyMce custom settings. Addsetting( ) with callback

Hi,

When configuring tiny we can customize it like this

context.Services.Configure(config =>
{
    config.Default()
        .AddSetting("media_dimensions", false);
});

But how do I configure if I want to customize an callback for exampke color picker?

In JS:

tinymce.init({
  selector: "textarea",  // change this value according to your HTML
  plugins: "textcolor colorpicker",
  toolbar: "forecolor backcolor"
  color_picker_callback: function(callback, value) {
    callback('#FF00FF');
  }
});

In C# ? 

context.Services.Configure(config =>
{
    config.Default()
        .AddSetting("media_dimensions", false)
        .AddSetting("color_picker_callback", );
});

I tried returning an javascript function as string for "color_picker_callback" but the TinyMce editor is then throwing an error. I guess it wont work to return an javascript function as a string, since it wont work to set values as "true" or "false" as strings.