FYI
In the EXOS Concepts guide for older versions, i.e. 12.X, there is a chapter called "Configuring Command Authorization (RADIUS Profiles)". It describes exactly what I want to do, but only when using FreeRADIUS. This chapter is removed in later concepts guide, bu the references to it is still there, just as you said.
In the
ExtremeXOS 15.7 User Guide the references are gone and the "Extreme-Shell-Command" is not even listed.
//Daniel