Preloader targeting specific MC

Hi,
I have spent awhile on this and am having a difficult time finding the right solution for a preloader within a movie clip that is targeting an event in another movie clip. So if I have a preloader located at _root.main and I need for it to load a movie clip called “_root.main.gallery_mc.image1”, and then continue on to frame 2 in the _root.main timeline. What would be the correct set up?

I’ve tried a few tutorials and I think I’m missing something obvious. Any helpers out there?
Thanks!