You can override the default Interactive shader node so that your custom version of the shader is created when you run 3ds Max.
To do this, create a new Interactive shader network.
Save your Interactive network to the \Users\<username>\Documents\3dsmax\plugcfg_in\ShaderFX\Scenes\StingrayPBS\ folder as Startup_PBS.sfx.
Now when you create an Interactive shader in 3ds Max, your custom version of the shader will be loaded.