How to create a password protected ad-hoc network on Yosemite when not connected to the internet

This is a more precise reframing of questions https://apple.stackexchange.com/questions/192077/no-secure-ad-hoc-network-with-yosemite (my use case) and https://apple.stackexchange.com/questions/182760/how-to-create-a-password-protected-ad-hoc-network-on-yosemite (not applicable here). Background info: With Yosemite (Mac OS 10.10) Apple removed the option to setup a *password protected* ad-hoc network. However, *Internet Sharing* allows to setup a secure network to share an internet connection from another network interface. Now, the problem is that the *Internet Sharing* network does not work for my use case, since it fails to start up when there is no internet connection to share. Peeking in the console reveals this message: configd: no interface for external service id This means, there seems to be no longer a possibility to quickly but securely connect two devices without bringing an external router, unless someone knows a trick or pointers how to configure the Software Base Station, or dive deep down into network config, maybe using ifconfig, natd, ipfw like here: https://blog.netnerds.net/2012/07/os-x-how-to-setup-nat-on-lion-and-mountain-lion/