THe most you can do is pull the cover off by removing the screw on the underside, and then remove the whole mirroe assembly by unclipping the 2 springs. To refit the only way is to put the springs on the door side first then clip onto the mirror part. I just had the mirrors off my EA as I wanted to paint the bit that surrounds the glass. I couldnt see any obvious way to remove the glass. It may just pop out but the amount of force I was putting on it would have broken the glass eventually.
If your friend has manual mirrors I have a set avalible.