Just be careful to make it a surgical strike. It doesn't take much to do the job. For an extra precaution, I had a turkey baster close by and once the anemone closed up around the fluid, I gently flushed the surrounding zoos with fresh tank water. That was about a month ago and I have seen no sign of the anemones since (there were actually two that had to be zapped).
Also, if you don't want to spring for the Joe's Juice, I have also used a mixture of kalkwasser powder & salt water, mixed into a thick consistency, but thin enough to be drawn into a syringe.