You may want to read the AD/DC sticky. http://www.gasgasrider.org/forum/showthread.php?t=7900
And the how to go DC thread. http://www.gasgasrider.org/forum/showthread.php?t=1859
Some info there.
As far as I understand you need DC power to properly run LEDs.
I did the floating ground conversion and run DC with a small sealed
lead acid battery on my '02 XC/EC300.
I suppose you could wire a dedicated / isolated, constant loss DC system
to just run the turn signals. Use a small 4-5Ah battery and charge it at
home before you use the bike. Might be more trouble than doing it right.
To make my conversion way easier I bought a used Full EC wiring harness
from a forum member from Canada to replace the XC harness from my bike.
Happy hunting and good luck.
Jeff