If I m not wrong .. there is a executable file conf.pl , in squirrelmail dir, just make changes in that file..using command
#./conf.pl
There are number of optons there
U have to give ur domainname,sendmail server and imap server.., U can give that in corresponding options..
Before giving imap server, be sure it must be started on ur server
#/etc/xinetd.d/imap
change disable=yes to disable=no
atart the service by:
#service xinetd restart
After that go to your web browser ,then type url as
127.0.0.1/webmail
or
localhost.localdomain/webmail
or
domainname/webmail
{
where domainname is your Domain......}
but before using squirrelmail , ensure that ur named ,httpd,sendmail must be restarted}
Gaurav