Extending the Asset URL Selector in SharePoint 2007 by adding filters or search

I'm having a bit of a problem here. We have a SharePoint site where users use a document library that contains about 1500 items. The users create content for several areas of the site and very often they need to insert a link to one of the documents in the aforementioned library. They use the standard url picker located on the toolbar of the content editor, which brings the Asset URL Picker up for them to choose the document they want to link to.

The problem lies in that looking for a specific document in a library that contains more than a thousand documents using the standar Asset URL picker is quite cumbersome. You can sort and go through the pages but it just takes too long.

So I've been asked to propose a solution and I'm thinking on customizing the Asset picker and may开发者_开发问答be add a textbox there where you can enter a search term and then display the matching documents in the standard listbox.

Is it possible to extend/customize the Asset Picker to do that? I've seen its standard properties and found no way of of getting it to filter the list contents.

Or should I build a new control to handle the picking?

My experience with MOSS is more about administration, but I've done some simple web parts and some other customizations.