I have no idea, but here are a couple of guesses:
one, there is a semi colon before your function declaration in your jscript_customradio.js file, which might mean nothing, but probably isn't helping:
;(function(){
the bigger one is that you should be waiting for your elements to be rendered before trying to alter them - and being that you have placed this script in the head, that hasn't happened yet.
I would try putting the function call in a document ready wrapper:
Code:
$(document).ready(function() {
$('input[type=checkbox], input[type=radio]').customRadioCheck();
});