How to intercept jQuery DataTables using chained Ajax

I'm writing a code that, among other things, needs to intercept the ajax of a datatable and add some data.

So:

$("#table").DataTable{
    ajax: {
      data: ...
    }).MyPlugin();

//In another file: plugin code
$.fn.DataTable.Api.register('MyPlugin()', function (params) {

    //something like
    $.ajaxPrefilter(function (options) {

    var paramsDataTableAjax = $.deparam(options.data);

    paramsDataTableAjax["additionalFields"].push({ "Key": DADO_ADICIONAL, "Value": "" });

    options.data = $.param(paramsDataTableAjax);
    });

    //more code ...
    });
});

I can not figure out how to do this using the plugin I created (MyPlugin ()).