Published on August 10, 2008 The easiest song to do this on that i found was "(F)lannigan's Ball" which is a downloadable extra..
You must choose EXPERT MODE.. :)
Guitar Hero 3 DropKick Murphys 517K Half a Mill Achievement
You could also try getting 500,000 on "Stricken" Expert Mode..
Guitar Hero III: Stricken 97% 507k! (A Tribute to Mattster)