From FFXI Wiki

A template to let you put hover over text in a line of text.

 {{H:text|Hover Over Text|Display Item}}

For no underline:

 {{H:text|line=no|Hover Over Text|Display Item}}

PLEASE NOTE: Having " will cause the display to break, so please use two ' in lieu of any ". They will not compile into italics, so do not worry.