8.2 UDB win32

I need update a one column in very large table. PK for this table -
generated always as identity :-(

I can't recreate table without generated always.I don't want write SP
or any non-sql script.
I'd like simple export & import with commit as I typically do

export  to file select pk, new_value as upd_col from table
import  from file commitcount xxx insert_update into  table(PK,upd_col)

Is it possible? or give me another solution, plz.

Andy