Legend: different family for title and labels

Hello All,

I am attempting to create a legend where the title has font family 
"sans" (or "Helvetica" in PS), and the labels (entries in the legend) 
have font family "mono" (or "Courier").  Would anyone be able to offer 
help on this?  I have successfully changed the entire legend family to 
"mono" using par() after the plot and before the legend, and I can 
change the title face using expression(), but not its family.  Is there 
a way to do this without separately placing the title inside the legend 
via text()?

Regards,
Marc