something like:
mkdir -p /etc/e-smith/templates-custom/etc/squid/squid.conf
cd /etc/e-smith/templates-custom/etc/squid/squid.conf
nano 20ACL40daytime
fill the file with something like:
acl someDays time MWF 10:00-11:00
(adjust the days/time according to your needs)
save and close the file with Ctrl-X, Y
then (you've to be in /etc/e-smith/templates-custom/etc/squid/squid.conf)
cp /etc/e-smith/templates/etc/squid/squid.conf/40http_access75AllowLocal ./
nano 40http_access75AllowLocal
edit the content and make it like:
http_access allow localsrc someDays
save it with Ctrl-x, Y
then
expand-template /etc/squid/squid.conf
service squid restart
Note: not tested, should work