I have tried this several times following the instructions. Each time I get a circle with a line through it instead of the apple logo upon botting from the USB drive. It's the "UnsupportedHW.png" image from the 1.6 .dmg.
Boot ROM Version: MBP52.008E.B05
It's a 17", not sure if that matters.
Yes, it matters that you are doing this on a 17". The 1.6 roll back would take a 15" or 13" MBP from B03 to B02. You have B05 firmware.