Dick Tuthill gave a nice description.  The only mods are:
 
NCAA has the same encroachment stuff as AHAUS (now USA Hockey)
 
It's the visitors stick down first only at center line face-offs,
at all other places it's the attacker's stick down first (this is
also the case for USA Hockey, but CHA (formerly CAHA) is visitors
first everywhere).  Some rules require the stick blade to touch
the ice (USA Hockey, NCAA), others need the stick blade to be flat
on the ice (CHA).  If it's at a face-off spot with a white strip
in the disc, then the stick need to contact the white bit.  The
guidelines in the clinics and manuals are that the puck goes down
the instant that the second stick touches the ice.
 
The previous poster said that the official holds the puck with
both hands.  This is not quite the setup.  The puck is held with
the non-whistle hand, the other hand may be nearby but is left
free so that some limited 'coaching' of the players is possible.
 
Graeme