Found this "workaround" on gpsdiscussion.com
Re: Navigon TS 7000T - any ways to be able to add your own coordinates
Not sure if this works for the 7000, but I have a navigon 7100 and found a file in the settings called Favorites.storage. This has my favorites in it. So if I have a POI where I only have the coordinates, I create a favorite, then edit the Favorites.storage entry and change the coordinates to the new ones. Then I make sure to make it reboot to pick up the changes.
I was able to find the file on my 5100 and when I opened it in notepad was able to view the coordinates. Haven't tried to change them yet. Hope this helps!
*edited* I just tried this and it does work, but it requires quite a bit of preplanning for your day of caching. It's better than nothing I guess. I just couldn't pass up the price and features of my Navigon, I'll live with this quirk.