Yes to access the mirror mounts is through the tweeter panel. It just pops off. Thiers 3 nuts that hold the mirror on.
Usually the studs that are into the plastic mirror gets broken/cracked. They sell pretty cheap on Ebay.
To totally "jerry rig" it you can drill a hole straight through where the studs are located and put a dome head bolt in, you can almost hang off those suckers
A little touch up paint and you'll hardly notice.....
hope that helps Tony!