Import Elm front-end from github into Phoenix back-end

My team is working on a phoenix/elm application, and have decided to keep the two projects in separate repos, and to 'point' to the elm application from the phoenix app. This is sort of new terrain for me, and I've been looking into different ways to accomplish this. I've tried importing the Elm app as a dependency via package.json, but I believe node_modules/ doesn't recognize Elm code. I've also tried importing it as a dependency via mix.exs, but again deps/ it looking for a exs file. Are there any other approaches to this?