KB813827 is talking about HTTP 1.1 keepalives, which are to do with keeping a TCP connection to the server open outside of a request. That's not the same thing as your problem, which is keeping a connection alive during a request. To configure the per-connection timeout see KB181050.
Assuming the programming angle here is that you are trying to write a server-side script that takes a long time to complete:
To avoid the request timing out, you need to have the server-side script return something every so often to reassure the browser that the server hasn't died and a result will be forthcoming.
How exactly you might do this depends on what server-side technologies you're using. Anything that waits for the entire response body and headers to be completed before sending anything back to the client is out. In eg. CGI you could return a response body with 'Transfer-Encoding: chunked' to spit out a few bytes every so often and keep the connection alive.
Alternatively, return a page right away and spawn the long process in the background, then have the client side page poll for its completion.