Migrating TWebBrowser code to TEdgeBrowser, how to send Post data?

Question

I am attempting to convert some code from TWebBrowser to use TEdgeBrowser, but I am having trouble figuring out how to send post and header data with an HTTP request.

Below is the TWebBrowser functionality that I'm trying to implement:

var
  VHeader, PostData: OleVariant;

PostData := VarArrayCreate([0, Length(XMLString) - 1], varByte) ;    
HeaderData := 'Content-Type: application/x-www-form-urlencoded'+ '\n';

WebBrowser1.Navigate(StrUrl,EmptyParam,EmptyParam,PostData,VHeader);

How do I do the equivalent with TEdgeBrowser, or in TWebBrowser with SelectedEngine := EdgeOnly?