OpenAL without installer

I have a few older projects in the wild and point Windows users to a XNA DirectX version and Linux/OSX users to a separate OpenGL Monogame download. The Monogame download, using Monogame 3.5, is standalone without an installer and I want to open this up to WIndows users. Everything is already setup for Windows with one exception - OpenAL. How can I easily add OpenAL functionality for users who don’t have this installed on their computers? Posts suggest I can do this by adding OpenAL32.dll to the game folder, but I’m not having any luck with this.