There isn't a good and easy way of doing this because it's easy to replace those characters, but it's hard to go back the other direction (you can't look up the category name in the database afterwards because it's been changed). The only reliable method to get around this problem would be to embed the category ID or link ID in the url. That in itself has problems, since it means you can have anything in the url and only the ID would matter (well, I guess you might not consider this a problem).

Adrian