Some guys will fill voids underneath with akemi to keep things from drooping. If its just caulked in you can cut with a razor knife and then use cedar shims and wedge around the piece a little at a time. Ive used screws underneath to remove bartops liquid nailed to plywood. You have to know when to stop, when to use brute force.
I do think you are better off getting someone to do this. It seems like a simple thing but experience does matter for something like this.
http://www.integra-adhesives.com/color-charts/
If you decide to wing it you need 2405 UbaTuba