There are VoxelMap topics at both the voxelbox forum and on MCF; no idea if either is more "official" though. The waypoints are stored within your vanilla minecraft installation (%APPDATA%\.minecraft\mods\VoxelMods\voxelMap\). The author has discussed both the IP-specific waypoints and waypoint storage location in a recent MCF post.
Thanks for that info. I didn't even think to look in the original Minecraft install location...because why on Earth would
I see that MamiyaOtaru says the waypoints are saved there so that you keep your waypoints even if you make a new MultiMC instance or whatever. It almost makes sense, but it would probably make more sense to put them in %userprofile% instead of %appdata% so they are saved per-user on that Windows machine. %appdata% just makes no sense because most people aren't going to have a .minecraft folder there in the first place.