making autocomplete source external site

Simple question, hoping there is a simple answer

I have the module set up, but I want to reference a different website altogether as the source for the autocomplete. What is currently happening is the api is prepending a leading '/' before the url forcing it to not work. Is there a way around this without hacking into a module?

Form Creation:

$form['test']['example'] = array(
'#type' => 'autocomplete',
'#data' => 'http://xyz.com/lookup.php',
'#title' => t('Name'),
'#size' => 30,
'#maxlength' => 50,
'#required' => TRUE,
);

Results in this output:

$("#edit-prescription-medication").autocomplete("/http://xyz.com/lookup.php", { "minChars": 0 });