Anne,
The alternating hot & cold washcloths to the face is to normalize sensory
perception of musculature in the jaw, cheeks and lips to reduce tonic bite- a
strong bite that the baby has difficulty releasing.  Gently rubbing or
stroking the washcloths in a circular pattern around one cheek, down the chin,
and up to the other cheek, then changing temps works well.  The important
thing to distinguish is if this is really a tonic bite.  Other, more common
reasons for biting are tongue retraction (if the lower lip contacts something
without the cushioning of the tongue, the bite reflex is triggered, but this
is a normal, phasic bite.  (bite-release-bite-release).  The tx for this is to
teach the baby to get the tongue out (and look for ankyloglossia if he seems
unable to).  Model tongue extension (have everyone stick their tongues out),
let mom gently tickle his lip and tongue with her nipple, waiting for the
mouth to be wide open and the tongue down before latching on, this can also be
done GENTLY with a finger first, and then put baby to breast.  Final common
reason for chewing is that the tongue muscles are weak and the baby is
compensating by using the jaw.  Try having mom slip a finger under baby's
chin, in the soft spot inside the arch of the mandible, supporting the tongue
muscles from below.  This is called sublingual pressure.  This is also done
gently.  It sometimes help to increase the pressure SLIGHTLY when baby
retracts the tongue and starts to bite.  There are other ways to strengthen
tongue muscles/increase muscle tone, but they are more complicated...could
refer baby to an OT or PT who specializes in suckling, or a feeding therapist
(an OT, PT or speech ther who specializes in oral motor feeding skills).  I
steal all my best suck stuff from their literature!  (What I don't make up
myself, that is).  It is very, very, VERY important to carefully position a
baby who is having trouble sucking.  Stability, support, and proper alignment
go a long way toward improving oral motor skills.  I probably should have put
this part first, but take for granted we all know this.  Bears repeating
anyway!
Let us know what happens with this little one.
Catherine Watson Genna, IBCLC