Input URL rather than browse for file

I have a podcast site and I use the “WP-iPodCatter” plugin for my RSS feed. When I write a new post I have to upload the MP3 in order for it to be recognised as the podcast in the RSS feed. The problem is that I host the MP3’s on a different server to the server my site is on, so I can’t upload them. Is there a plugin or some code I can use to change the upload box from browse for file, to enter a URL? This might not be a plugin issue, I just need some way of it recognising its a podcast without uploading it. Thanks in advance ??