> I suppose you could use HTML and wrap the values in [...] CDATA
This would probably not help in many circumstances.
> I don't know of any way to preserve such text formatting within a MODS element, but would be pleasantly surprised to learn of a way to do so.
An other horrible hack, which I DO NOT RECOMMEND at all in a large scale nor for export, would be to use characters from
http://www.unicode.org/charts/PDF/U1D400.pdf for italics or bold, but that is AT YOUR OWN RISK and I would NOT really recommend it, because (among other things) this text will be (almost) no longer searchable, because you cannot use any letter other than ASCII letters (a-z), and because only a few devices have fonts for these characters. In some limited
circumstances, this may »look fine» though, and it may be useful as a last step before printing for exampel, but I would strongly recommend to convert it before any export.