Building is done through cargo as normal but you need atleast rustc 1.43.0-nightly.
On Windows make sure you have (pre-)compiled GLFW3.3+ libs installed and
an environment variable named GLFW_MINGW_LIBS pointed to the folder
containing the right libglfw3.a (for mingw-w64 if using the GNU toolchain).
Linux is currently not supported but it should be easy to get it working. Just make sure you have the proper compiled glfw libs.