For the small ones I bought one of those multi-pack thingies like a jackknife...but anything larger than a 15 probably needs too much torque for those.
I bought a bunch of the torx sockets and usually carry a few with me...if it is the same size as the ones on the seat belts then that would probably be a t-50...$8 each or less...
If you need to know the size of the socket/allen/torx it is usually listed somewhere...like the Haynes manual (that costs more than a few torx sockets) but I don't have mine handy or I'd look it up for you...
The on-line repair manual doesn't list the size, but lists the part number...56094 or 56904-s...search on that...or maybe visit a Ford dealership if that's handier...but not sure if that's the part you need...
Check out the on-line repair manual and punch in the year/make/model then find the trim...interior...and look at the diagram...get part numbers and go from there.
not sure if this link will work...it's the interior console diagram and shows all the parts and numbers...also might give you an idea how to take it apart without breaking something...
http://arrc.ebscohost.com/statics/p5/images/sm/isbn_graphics_complete/9131/chiltonimages/8555/85556055l.gif
If that don't work...go here...and log in...
http://www.therangerstation.com/forums/showthread.php?t=319