Perhaps if I explain how the lte-ie7.js works, it might help you make it work. It goes through the DOM and finds any element with an "icon-" class and then inserts proper HTML entities inside it. Therefore, if the document has not yet finished loading, it won't work.
lte-ie7.js file is currently using window.onload, but if you're using your own custom setup and want to load it via js, you should change it to a self invoking anonymous function like this:
(function() {
function addIcon(el, entity) {
var html = el.innerHTML;
el.innerHTML = '<span style="font-family: icomoon'">' + entity + '</span>' + html;
}
/* and the rest of the code... */
}());
I hope this helps.