Actually, this is a full InvokeAI install, so you can still use the command line. :3
The "helper.bat" basically calls the InvokeAI installation via the command line. So you can make a copy of that one and adapt it to your needs. :)
Edit: You can update models to diffuser from within the UI, when you load it normally -> Edit -> Convert to Diffuser. The button is a bit hidden, sadly. :/