if you have stored the oldid and the newid, you could use the placeholder tableselect to get one based on the other. at least it seems so

edit:
If you have joomla on the root domain (domain.com), and the url rewriting for deleting the index.php is activated... do you need the ErrorDocument 404 directive? Some example of this?

We don't have the oldid stored anywhere. We just copied over the products and articles and each article received a new ID when it was created in Joomla. If it isn't as simple as putting the old URL in the From and the new URL in the To, then it probably won't work for us anyway. Thanks for trying though.

Right, which is fine with me. I was just looking for an extension I could create these redirects with so we didn't have to create them outside of Joomla.