Liberation Fonts & Font-Mapping 101

[Jorge Fábregas]

Hello guys,

I'm once again fighting with fonts in Firefox and I'm using the  "Font finder" 
add-on to see what font is being requested for any section of a page.  I 
noticed that there are quite a lot of pages requesting the "calibri" typeface 
(which is the default for Office 2007).  When I go to my terminal window and 
type:

fc-match calibri

I get: DejaVuSans.ttf: "DejaVu Sans" "Book"

What file do I need to edit in order to change this mapping to "Liberation 
Sans"?  I did a search (search within files) recursively in the /etc/font/ 
directory but couldn't find the word "calibri"...so I'm guessing "Dejavu 
Sans" is the default typeface I get when there is no mapping for it. I just 
did:  fc-match whatever and indeed I got "Dejavu Sans".  So...how do I create 
this mapping "when requesting "calibri" use ------------>  "Liberation Sans"?

Thanks in adance,
Jorge