Yes, after you model a mesh you should be able to vertex paint it in the same modeling program and then export it to Studio as you normally would. The emission is basically the MeshPart set to the Neon material. Take note that this will not work if you texture the mesh.
I found some… interesting example meshes to help illustrate my point. They are all set to the Neon material.
Left: untextured mesh without vertex colors. It glows, but there is no color differentiation because there are no vertex colors.
Middle: textured mesh without vertex colors. It does not glow due to it having a texture.
Right: untextured mesh with vertex colors.