Redirect a HTTPS CONNECT using squid

This probably won't work the way you think it does. You can't just redirect an HTTPS site - you need to "man-in-the-middle" it. This implies either installing a root cert on each system (and compromising their security somewhat so you can read the traffic), or your users getting a warning which they should not be being taught to ignore.

See http://wiki.squid-cache.org/Features/SslBump for specifics on how to do this. (But please don't do it).

In addition, unless you are configuring SQUID as a proxy, (ie you are not using a transparent proxy, which would seem to be the more logical solution), you will need your router to additionally intercept traffic on port 443 and redirect it to the squid server - you will find there is a similar rule for port 80 traffic.