You can now find the postmaster and use the following commands:
which will list the commands you can use
say list ta'veren
which will make the postmaster compile a list of the ta'veren, as put together by players
say add ta1/ta2/ta3 etc. name name
which will allow you to remove a previous ta'veren 1/2/3 record and change the names on there.
As the Seanchan became human, their Sei'taer all became Ta'veren, so there might be two Ta'veren at each rank for the forseeable future. Hence why you can list two names for each rank.
You say 'list ta'
The postmaster starts rifling through his records.
The postmaster writes down a few names.
The postmaster makes a few notes.
The postmaster checks his work one last time.
The postmaster shows a sheet of paper to you.
It bears the Seal of the postmaster.
There is something written upon it:
Ta'veren 1: ryalth varcoz
Ta'veren 3: harun milian
Ta'veren 4: fermin