Help with Ajax Autocomplete

[eluser]josebalius[/eluser]
Sorry for the third post in a row (is it allowed?) But now I am using the:

Code:

$this->ajax->remote_function('elementforresult', array('url' => '/checkuser/');

On a button however I don't understand how I would be able to set a parameter? For example if I have a form with a field that I want to be send when a user clicks on a special ajax button, how can I make that remote_function grab the value by its ID or something? I just don't know how to call it with the PHP options.