I went through the same thing. Surround the old emblems with blue painters tape. Slowly pick the edges of the old emblems with a plastic scraper...preferably a tool used to install vinyl lettering. Once you get all the letters off, use the plastic scraper to gently remove the big pieces of residue off, then use Goo Gone to get the rest off. Then take a soapy rag and wipe the Goo Gone residue off. Get some transparent tape and put it over the top of the new emblems, then put a second piece over the top of that piece. You can then pull the backing off of the adhesive side of the emblems, they should be a little cushiony. Let it air dry and get tacky for a minute or so. You should now be able to install all the letters over the area you previously blue taped around. Line it up (you should be able to see through the transparent tape) and push in firmly. I say push firmly because your installing them on an uneven surface...at least on the back bumper anyway. Let it sit for an hour, then gently pull off the transparent tape.
