The rosters are simple to install, just paste them into your documents for NFL Head Coach.
These rosters aren't ready for use yet, they're scaled inaccurately and generous. (The mod hadn't fully translated all of the translations from Madden 08 to HC06 at the time.) The Madden 08 PC 22 rosters should be done within the next few days, then he'll get to work on the final rosters for NFL Head Coach.
Trust me on this one, wait a month or two until the final rosters are released before starting a career with them. You can use the updated stadiums and jerseys with the original rosters while you wait, just start a career without the mod installed, then install the mod after your career file has been made.