Make sure the wire wool is grade #0000 (very fine). This should prevent any scratching off the pipes.
Wearing a pair off rubber gloves to protect your fingers and hands, dip the steel wool into a bowl of soapy water, and simply rub gently around the pipes, removing as much off the oxidized exhaust soot.
Be patient with this, and you should get 'em nice and clean.
Then use the Autosol cream - simply apply finely using a soft microfibre cloth, making sure to continue polishing the pipes rather than just 'applying' the cream, and wipe it off using a dry microfibre towel. You will notice that the cloth goes pretty black - even if the pipes were VERY clean - this is normal.
Job done :icon_thumright: