Welcome aboard.

Your reluctance to feed it live animals, and mice (dead ones), is understandable. However, I do hope you change your mind. Life isn't fair and keeping the snake alive is a priority once you decide to keep it and mice might have to be sacrificed to ensure its wellbeing. Earthworms aren't good staple food and shouldn't be used over longer periods of time.

It is my understanding that earthworms (Lumbricus) are difficult to keep alive over long periods of time, especially compared to the species that are used in indoor composts (Eisenia). I've only kept them for 2-3 months at a time. What I do know from experience (I use them as bait as well as "snacks" for my own snakes), is that it's important to provide enough humidity and not expose them to direct sunlight. They use decaying plant material for food, which means that things such as decaying leaves need to be provided for them. In my humble opinion, it's not worth the trouble.