No idea, but I suspect it's not possible - EM is really a management
tool, and there are some things that can only be done from Query
Analyzer.
If you mean that you want to add NOT FOR REPLICATION to an IDENTITY
column, then unfortunately there's no direct way - the ALTER TABLE
command doesn't support this. Probably the best solution is to create a
new table with the definition that you want, copy the data into it,
drop the original table, and rename the new one. See CREATE TABLE, SET
IDENTITY_INSERT, and sp_rename in Books Online.
If this isn't helpful, I suggest you post some more information about
exactly what you need to do, and the SQL commands you're using.
Simon