Quick play or Career: Play Slow Ride on Expert. The easiest song on all difficultys.
Having the no fail cheat on wont work so if you've put any cheats on make sure they are set to off.
If you can 5 star songs on Medium you'll probably be able to do this. All this is, is playing an easy song on Expert. Having all the audio settings set to 0 makes hardly any diffrence to me. Infact you don't have to have them all down to nought till nearing the end of the song. Just have the audio on for nearly all of the song and then switch them to zero before the ending by pressing start, options and then audio.
You might find yourself in the red if you fail on expert usually. The rock bar (bottom right hand corner of the screen) goes to red easily on expert remember with just a few missed notes. Try to hit every note possible.I was in yellow for most of it as I am an average player.