I just received an enquiry from a guest who is keen to watch a bit of football while in Rome and in particular to see FC Lazio in action. Though I am a Roma fan myself, I didn’t point out the error of his ways but gave the following advice:

The Capena side have just been moved up a league and they have a spanking new stadium so you  could do worse than see a match there if the season has started by the time you arrive.

This site looks excellent for your purposes: http://www.footballinrome.co.uk/index.html – it has this to say about Lazio:

Lazio’s centre of operations is the complex at Formello, a few miles north of Rome. This is where training and friendly matches (sometimes open to the public) take place.

Formello has just launched a website – part of the official Lazio site – where you can read exciting gossip (only in Italian at present) such as who arrives first at training and who leaves last. The site also promises webcams, enabling you to spy on the players in training(!). The address: http://formello.sslazio.it.

You could try posting a question on this English language forum for Lazio fans  http://forum.lazioland.com/.