myhttp.js

var sys = require('sys');
var http = require('http');
function MyClient() {
    http.Client.call(this);
    this.setRequestCtor(MyClientRequest);
    this.testProp = 'myclient test prop';
}
sys.inherits(MyClient, http.Client);
MyClient.prototype.tester = function() { sys.puts(this.testProp); }
exports.MyClient = MyClient;

function MyClientRequest() {
    http.ClientRequest.apply(this, arguments);
    this.testProp = 'myclientrequest test prop';
}
sys.inherits(MyClientRequest, http.ClientRequest);
MyClientRequest.prototype.tester = function() { sys.puts(this.testProp); }

request-ctor.patch

diff --git a/lib/http.js b/lib/http.js
index 1f3537b..58506c7 100644
--- a/lib/http.js
+++ b/lib/http.js
@@ -835,6 +835,12 @@ function Client ( ) {
   httpSocketSetup(self);
 
   var parser;
+  var requestCtor = ClientRequest;
+    self.getRequestCtor = function() { return requestCtor; };
+  self.setRequestCtor = function(ctor) {
+      if(typeof ctor != 'function') throw new Error ('Request Ctor
+      requestCtor = ctor;
+  };
 
   function initParser () {
     if (!parser) parser = parsers.alloc();
@@ -1002,7 +1008,8 @@ Client.prototype.request = function (method, 
     url = method;
     method = "GET";
   }
-  var req = new ClientRequest(this, method, url, headers);
+  var requestCtor = this.getRequestCtor();
+  var req = new requestCtor(this, method, url, headers);
   this._outgoing.push(req);
   if (this.readyState === 'closed') this._reconnect();
   return req;

test-myhttp.js

var sys = require('sys');
var http = require("myhttp");
var client = new http.MyClient();
client.port = 80;
client.host = 'www.google.com';
client.https = undefined;
client.credentials = undefined;

var request = client.request('GET', '/'
                             , {'host': 'www.google.com'});
request.addListener('response', function (response) {
  console.log('STATUS: ' + response.statusCode);
  console.log('HEADERS: ' + JSON.stringify(response.headers));
  response.setEncoding('utf8');
  response.addListener('data', function (chunk) {
    console.log('BODY: ' + chunk);
  });
});
request.end();
client.tester();
request.tester();