For the 3dUndump solution, you will probably want to add the -srad option to place a sphere down at each location.
You can also use the Tagset editor plug-in for this purpose. The Tagset editor can read in files with the following format:
"tag1" 50 50 50 1
"tag2" 100 100 100 2
"tag3" 100 50 50 3
"tag4" 50 100 50 4
There's a label in quotes (single or double), the x,y,z position and then an arbitrary value to associate with that. The file name should end in ".tag", e.g. taglist.tag. The Tagset editor is handy for moving to the tag points quickly.