The instruments don't know that you're inverted. It'll tell you if youre above or below GS, and right or left of course.
So.... if you're above GS, go down (pull back on the stick if you're inverted), vise versa if you're below. If you're right or left of course, obviously if you're inverted your right and left are switched, so you're backwards. But also remember that when flying inverted your lift is reversed and your horizontal component of lift works toward the bottom of the plane. That is, if you bank to your right, the plane will turn to your left.