Restricitng certain pages to certain IP's

We are trialling a system of allowing our students to use Webmail
(the main restriction being a lack of resources, rather than
phiosophical). We want them to only accesss webmail (hotmail
etc) from a couple of terminals. Is there a way in Squid to achieve
this. I have looked in the FAQ but could not see what I want....

IF IP is in approved list allow page otherwise deny.

I know how to deny it to all my terminals but not to a few. Any
clues or pointers appreciated.

Cheers,

--
Simon Bryan                    sbryan@olmc.nsw.edu.au
Information Technology Manager sbryan@mpx.com.au
OLMC Parramatta