I use Genesis Savestate Viewer. It's basicly the same as vSNES, but for the Genesis. It's better for sprites than maps in my opinion.
I don't know the rules about posting links here so just google "genesis save state viewer" and you will find it at the top of the results.
I actually tried using it for Landstalker a couple years ago & I gotta say you are better off using an emulator with that WTW code, just make a save state everytime you enter a room because you can get stuck very easily in some of them.