functions.php

<?php

wp_register_script( 'head-load', "/wp-includes/js/head.load$suffix.js", array(), '1.0.3', 0 );
wp_register_script( 'my-head-loader', "path/to/my/head.loader$suffix.js", array( 'head-load' ), '1.0.3', 0 );

$scripts = array(
  'head'         => 'wpHead',
  'myJqueryFile' => "path/to/my/jquery.file$suffix.js",
  'jQuery'       => "//cdn.domain.com/jquery$suffix.js",
	'underscorejs' => "path/to/underscore$suffix.js"
);

// Rename head to use wpHead.
wp_localize_script( 'head-load', 'head_conf', $scripts );

// Keep HeadJS defaults and do whatever I want
//wp_localize_script( 'head-load', 'prefixScripts', $scripts );

wp_enqueue_script( 'my-head-loader' );

head.loader.js

wpHead.test("undefined" !== typeof jQuery, [prefixScripts.underscorejs, prefixScripts.myJqueryFile], [prefixScripts.jQuery, prefixScripts.underscorejs, prefixScripts.myJqueryFile], function(){
  // Finally do something now that everything is ready!  
});