Sorry for the delay,
For my small flags, I just used the type that attach to a window... You know the plastic rod ones. To attach to the bike, I used a piece of aluminum angle and two U bolts to hold it to the sissy bar. Then I put the flags on the aluminum and put a screw into each side to make sure they stay on.
I ran two, one higher up for the American flag, and a lower one for my USN flag on one side and a POW/MIA flag on the other side.