Well, one workaround would be to make an index.html that has a meta-tag to redirect to index.pl. However, that is not the most desirable solution. You should contact your web-host and see if they will modify the server for you, so that if it does not find an index.html it will load an index.pl for you. However, the method to do this varies depending on your web-server, so your best bet, as I said, is to contact whoever's hosting it for you.