buddy

Look at the map a few posts above. That is where I did this insanely stupid task. Face away from the screen(up). Stand still and dodge. Then walk north to where you were originally standing and repeat...199 more times (at least).
Tips that helped me...
Have no-encounter ability enabled - a must
Turn down lights in room - helps you to see flashes easier.
Elimnate all distractions - i.e. pets, phone
Focus your eyes about halfway up between Tidus' head and the mini-map. Don't look at Tidus.
Count the # of dodges out loud (whisper them)
Stop every 20-30 to rest your eyes, but pause right in mid-jump backwards. That way you have time to get back into it when you restart it.
Stay in that 3-strike zone...
Give yourself an extra dozen dodges in case you mis-counted. (You don't want to go back to the Inn to find you did 198 or 199)
Good luck