It seems to me I struggled with the same question. That was a long time ago, so I don't recall whether I found it couldn't be done, or I chose to leave them as they are. It might be the latter, because if the underline is removed they'll appear the same as other fields that are blue (because they're internal search links).
<linkdefs> <underline_record>false</underline_record> <underline_memo>false</underline_memo> <underline_combo>false</underline_combo> </linkdefs> This works well for all fields except for the people fields (producers, directors, actors). These data are still underlined. Is there an addition setting in the skin engine which I miss or is it not possible to turn these underlines off? Thanks for any help.