This is done easily through your Control Panel. Simply log into your Control Panel, then select "Mail" from the icons, then click on "Forwarders" link. Click "add forwarder" and then fill in the name of the alias, and then in the last field, enter the address where you want the mail sent to. This can be to a POP3 mailbox on the same account, or an external account by entering that email address instead. Click the "Add Forwarder" button, and it will create the forwarder.
