Conditional formatting list box/query

I have an unbound list box on a form that is populated by a
query.  The query returns records of information about
healthcare facilities; each record is a facility name (and
key) and a set of four dates representing essentially the
last updates of different sets of facility related data.
Users select a facility in the list box and from there
navigate to related forms for the selected facility.  

I want to apply conditional formatting to these dates, such
that they appear red when a certain time threshold is
exceeded.  On a similar report, for example, I apply
conditional formatting using the Datediff function, but
this is easy on a form.  It seems that to do it in the list
box I have to apply formatting somehow within the sql of
the query that populates it.  Is it possible to embed
conditional logic (and the datediff function) in a jet sql
query?  Or am I going to have to redesign the way the list
box is populated with a vba procedure that would allow me
greater control over fields?  

Thanks in advance,

J.D.
Novice access developer