I am also surprised that they are asking for certification...unless they are asking that you produce a certificate of attendence saying that you sat for an EKG course. I would check into community colleges, and maybe even the yellow pages or newspaper. I noticed that some of the schools
for CNA offer the course, but I have wondered if it is more generalized, since CNAs don't normally interpet. In NYC, they list places that offer EKG courses all over the classifieds. I would just be sure that they are really covering all of the rhythms, because placing the leads is one thing...the licensed nurse is responsible for monitoring for early symptoms and responding on a timely basis.
Also, call your old school, maybe they know of some places that offer the course. I took one in New York at Beth Israel School of Nursing. It was excellent! I did not utilize the skill, just yet, but their 3 day class taught me so much! I remember trying to figure out how on earth they would be able to cram all of that in three days, but those women sure did, and I still refer to my notes every now and then.