Including CI snippit in another site

[eluser]suppster[/eluser]
I would like to include a CI comment form in selected pages in an existing non CI site. I've tried using

Code:

$_SERVER["REQUEST_URI"] = "cms/2";

//Set GET action,method params etc

require_once "path/to/index.php";

in a file in the codeigniter root directory, but get the following error:

Fatal error: ob_start() [<a href='ref.outcontrol'>ref.outcontrol</a>]: Cannot use output buffering in output buffering display handlers in C:\xampp\htdocs\web\codeigniter\system\core\Exceptions.php on line 166

But when I include the above code in a file outside the codeigniter root I get

Your system folder path does not appear to be set correctly. Please open the following file and correct this: index.php

Any ideas? Thanks