For anyone wondering, this is how I was able to do this:
c::set('routes', array(
array(
'pattern' => '(:any)',
'action' => function($uid) {
// Does the url contain uppercase characters?
if (preg_match("/[A-Z]/", $uid)===1) {
// Redirect to lowercase url
go(strtolower($uid));
} else {
return site()->visit($uid);
}
}
)
));