Commissioners and such for ICZN?

[Robin Leech]

Can anyone tell me the process by which a person becomes a commissioner for the International Commission on Zoological Nomenclature, and how a person becomes a member of the Executive Committee of the International Union of Biological Sciences (IUBS).
This is not spelled out anywhere in my documents.
Chris Thompson and Phillip Tubbs - are you out there?  
Robin Leech