How to allow hot links in photo description ?

How can I allow hot links ( url's ) in photo description ?

thank you

The way the uploader works is that it is shared between all the modules that allows uploading of content, files, videos, photos, etc.; each module uses the main files uploader.  I tried changing the description field for files so that members could include a graphic to show what the file was; and had trouble with it because of the nature of the form.  I gave up on having it where the members could do it at the time of the upload of the file and instead change the edit form to allow HTML and added a custom version of a TinyMCE toolbar and set the HTML => 4 for the form to use my new toolbar.  The way it works for my members on files is that they have to first upload the file, then go to the file browse page and click on the edit button in the actions block.  They can then add an image, and even change the font size and attributes such as bold, to the description block.  Such things as Javascript code is blocked by the normal htmlpurifer and TinyMCE editor.

I would like it to be at the time the file is uploaded but when I was working on this, I just could not get it to work properly due to the way the upload form is done.