This may not be what you're looking for, but if you go to the UI\FrameDef\Glue\PlayerSlot.fdf file in the wc3 MPQs (War3xLocal.mpq) and open it in WordPad or NotePad you can edit the names that appear for races on the menu. Unfortunately, this method only works for Mods, not maps, because the new version of the PlayerSlot.fdf file has to be in mod. I have not yet tried importing such a file into a map, but it would be a worthy test.
This method is also useful because you can add races to the menu screen (I have a Race Mod with six races that all appear in that menu for select race) although added ones are not actually functional. (if you click them it selects random instead, don't know why)