Overriding wp_handle_upload to crosspost to a CDN

Hello,
The new flash-based media uploader works great for uploading files locally. However we recently moved to hosting all the media for our site on a CDN. There is no easy way to override the wp_handle_upload function (it does not have an if function_exists()) block around it like most) to use my CDN-posting function instead of doing a local file upload.

I’ve written my own modified version of this function and have it working fine, but I really don’t want to commit changes to the vendor portion of the wordpress code in our repository. I’d like to make this change using our plugin instead, just like everything else I’ve done so far has been done… but I’m just not seeing a way to make that work without changing at least one line in the main WP source.

How can I either override the wp_handle_upload function without modifying the wordpress codebase, or alternately set up the admin media uploader to use a different function (my own) to handle POSTs instead of using wp_handle_upload at all in that instance? Thank you.