As d4n0 suggested, you can use the export feature together with the Taglist-Tag tool.
Create a new export by going to Tools, Options..., then to Export. Add a new export and name it whatever you want. You can then use the following for backing up the title, artist, album, track number, year, genre and comment:
RECORDLINE01=%title% | %artist% | %album% | %year% | %track% | %genre% | %comment%
Save your changes and then select File, Export for exporting the tags of the selected tracks.
When restoring the tags, use Convert, Taglist-File - Tag. Select the exported file and use ...
%title% | %artist% | %album% | %year% | %track% | %genre% | %comment%
... as pattern.
Edit: Or you can use my experimental program together with MP3Tag's clipboard functions. However, I do not take any responibility if the program fails or if your computer explodes.