How to receive a data parameter WebAPI

I get an xml in my webAPI and deserializo it.

What I did, I got the exact template of the XML that I'm going to receive and I make a call on my service locally, just for the test effect. So long, I can get the fields I need. However, when I publish, in the documentation of who is going to send me, they inform that they will pass this same XML, but within a data parameter. I would like to know how to prepare my url to understand and capture the xml with this parameter. Until then, I make the request, sending via body, but I do not use it.

It will probably come with date = xml with content.

namespace WsCliMotoristas.Controllers
{
    public class XmlController : ApiController
    {
       [HttpPost]
        public void Post(HttpRequestMessage xml)
        {
            string idumov, identificadoralternativo;
            idumov = "";
            identificadoralternativo = "";
            try
            {

                string body = xml.Content.ReadAsStringAsync().Result;
                var Schedules = System.Xml.Linq.XDocument.Parse(body);

                foreach (var elementos in Schedules.Root.Elements())
                {
                    if (elementos.Name == "alternativeIdentifier")
                    {
                         identificadoralternativo = elementos.Value;


                    }

                    foreach (var historicos in elementos.Elements())
                    {
                        if (historicos.Name == "activityHistory")
                        {
                            idumov = historicos.FirstAttribute.Value;

                        }

                    }
                }

                GetEntrega entrega = new GetEntrega();

                entrega.GeraEntregaAsync(idumov);
            }

            catch (Exception ex)
            {

                Console.WriteLine(ex.Message);
            }

        }
    }
}