Merging is now part of Neumann. More correctly Sennheiser bought Neumann in 1991, and Merging last year. The MT48 interface is based on the Merging Anubis.
The MT48 manual can be downloaded on this page. The way they expect people to use it is as a USB interface. In the manual there is the usual "works on Mac without drivers, but install our proprietary crap for full functionality." This means there is a degree of class compliance. It may be worth asking Neumann exactly what functionality is lost when using the MT48 without the proprietary software, called 'MT48 Toolkit'.
When it was advertised the marketing said that all functions were accessible from the touchscreen on the interface itself, which would be good for Linux. Also there is a remote control app that uses a web browser, which would also be good for Linux. Unfortunately the way the manual tells us to access the web app is through MT48 Toolkit.
References to the ethernet port describe connecting other interfaces, particularly Merging interfaces, and putting the MT48 onto your network so the remote control app can be used. There is no mention of using AES67 as the primary connection to the computer. You would think it would work using the Merging ALSA driver, but you really would have to try it, and it may be fiddly.