Render Page Into Custom Output?

Let´s take an usual aspx page, ~/admin/template.aspx

The admin folder allows only "Admin" roles for example.

Now I don´t want to run the template.aspx as usual, but I want it be called from a active process. Let´s say I´m on ~/admin/buildMyStuff.aspx and there I´m collecting some data, I now have some querystring, like "?do=this$andDo=that$index={0}". Now I want, using this template, loop through my data and generate my ouput, putting it then for example in a static html or in a text file or something else.

How should I do that? Calling it as new request, waiting for response? What I have to do, that it is running under the "Admin" role, or is it doing it automatically, since I already am admin?

Or is there another possibility, that allows me to run the template page and specifiing my custom htmltextwriter as output?

EDIT:

public static string RenderPageAndGetHtml(string pageUrl, string pageQuery)
{
var sw = new StringWriter();
var wr = new SimpleWorkerRequest(pageUrl, pageQuery, sw);

[Code]....