AFAIK it is not possible because you can not select the uv map in the 'Octane UVW Projection Node' like in the UV node in cycles. Always the active map (in the mesh tab) is used. Would be a nice to have this feature in the future!
Max plugin doesn't have multi UV support. I turned to Blender in hope, that maybe Blender has. Nope, it doesn't !! After all those years still a very incompetent renderer for serious projects.