Change Parameters Of Loaded Script After Page Load?

I doubt this is possible, but I have no idea what actually happens when a page loads, so I thought I would give it a shot...

if a js file that is loaded externally has parameters, is it possible to turn those parameters into variables, giving the user the option to select the variable's value after the page has loaded?

maybe a concrete example would be better...

in google maps, the api is loaded like this:

<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"></script>

but if you wanted to specify that you want the api to function in Spanish, you load it like this:

<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false&language=es"></script>

and that language=es is the one that I want to change. But I can't seem to make it into a variable on page load, like this:

<script type="text/javascript">
var lang="es";
</script>
<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false&language=lang"></script>

much less make it changeable once the page has loaded.

I have a feeling that this is a really dumb question, but can it be done without reloading the entire page?