EM SLOEs (and they are pretty unique in this) have a very specific format (
here's an example of what older ones looked like). To be honest, I really wouldn't use those for anything except for applying EM. Now that said, you could certainly get LORs from other
providers, including EM
providers, to fulfill the 3 LOR requirement. Just make sure you read the program specific requirements, because some may require x number from the same field.