Look for dog trainers that will train the dog to be a service dog

Depends on the dogs willingness to learn. A lot of dogs wash out of training. It's not for every dog. I would not attempt to train a dog unless I was a dog trainer. The law says the dog must be trained "tasks" that are directly related to the persons disability.
Alerting is not a trained task. I would say hire a trainer. Discuss what you need the dog to. Have that person evaluate the dog. For epilepsy it's good to have the dog hold your to lay on your upper body or roll you on your side during a seizure and bark if in a public place. Good Conduct Citizenship Training is a must, as your dog will be out in public. My dog came house trained and well behaved, but it took a year of private lessons to call her a"service dog". She doesn't like the grocery store. Too noisy, aisles too thin, whats with those carts, all those smells, 2 weeks ago somebody ran over her tail.
Dogs require drilling to keep them fresh. Mine doesn't get the treat until she rolls me over. ( if I'm on the floor, roll me over)
Once in a blue moon I have an access dispute. The service dog law has been around since 1990 and by now businesses should know it. I carry a copy of the law with me at all times. I remind the business that the justice dept says I have the right to be there and give them there very own copy of the law with the phone # on the bottom if they don't believe me.