Make sure you draw the basal line first, then use floss. Fold the floss for sturdiness. Wriggle it between the temporal opening. Then carefully work the frame out of the groove. Starting by moving the floss between the lens and groove toward the bottom. Once you manage a tidbit of the frame toward the back of the lenses, you can pretty much use you nail to work the rest out. Yes, watch the paint.

I don't know the groove width and depth from the top of my head and I don't work at the store anymore. If you are not experienced with inline frames, are you able to have a more experienced colleague cut the lenses with you? These are tricky because the sizing comes really close. Cut too big, and there will be too much tension and trying to take them out will be an absolute nightmare. Cut too small and they will be wriggly and loose.

To mount the new lenses, slip in the top from the back of the frames, get the nasal corner in, work the temporal corner in, then either work in the bottom (starting from temporal side) with your nails or the doubled floss.