Changing Xml Element Name Dynamically?

I am trying to change Xml element name based on a rule during serialization.

Of course,I can manually add ElementName attribute manually but I have more than 1000 property in my class to be serialized.

In addition to that I don't want to change all property names only some of them which don't have Xml ElementName attribute.

For Instance ;

public class ToBeSerialized()
{
public string FirstName {get;set;}
public string LastName {get;set;}

[XmlElement(ElementName = "MyHome")]
public string Home {get;set;}

}

My Naming Convention for the ones don't have ElementName attribute.

public string ChangeName(string item)
{
   if (!propName.Any(p => char.IsLower(p)))
            {
                return propName;
            }

            var builder = new StringBuilder();

            for (int i = 0; i < propName.Length; i++)
            {
                if (i != 0 && char.IsUpper(propName[i]))
                {
                    builder.Append("_");
                }

                builder.Append(propName[i].ToString().ToUpper(new CultureInfo("en-US", false)));
            }

            return builder.ToString();
}

Desired Xml

<ToBeSerialized First_Name="Name" Last_Name="Surname" MyHome="Mine" />