How can we open our firewall to allow Google Analytics?

We operate a firewall which blocks all internet access for users on our company network. However we would like our intranet to track users with Google Analytics.

How can we open up our firewalls to only allow access to googleanalytics.com ?

I have searched Google extensively and it seems Google do not provide an IP range which we could use in our firewall config.

How can we white-list googleanalytics.com ?

As far as I am aware, it is normal HTTP / HTTPS traffic to the following URL's that is required:

https://ssl.google-analytics.com/__utm.gif
http://www.google-analytics.com/__utm.gif

and

http://www.google-analytics.com/ga.js

So, port 80 for HTTP, port 443 for HTTPS and the site(s):

ssl.google-analytics.com
www.google-analytics.com