Not really. You can open just that file, but you won't be able to see anything.
Here's what you can do:
Highlight MainHUD and hit the up arrow with the line over it. That moves it to the top.
Then do the same to Experience within MainHUD.
This will make the Experience window show on top so you can edit it more easily. Just be sure to delete eq2ui.xml and eq2ui_mainhud.xml from your folder if the game patches and something stops working.