The latest
patch should help with shifting character positions due to alt-tabbing.
You just need a hex editing program to edit the save data files (regardless of extension). Since you may already be at least vaguely familiar with hex numbers, as opposed to decimal, using a hex editor should not be that much more complicated than a text editor (just a little scarier at first).
In the
Teleporting anywhere post I listed a few freeware hex editor programs.