I believe you can code these kind of things into your Scripted RC yourself.
Explore the GUI Objects like so.. (You can find a lot of neat things this way :3)
PHP Code:
//#CLIENTSIDE
function onCreated() {
for (temp.cont: GUIContainer.controls) echo(temp.cont.name);
}
Find the GUI Object name for the Filebrowser, and add a script event function to "hook" it. I.e: Object.onKeyDown()