Off-Topic: setting field authorities on a physical file on a DB2/400

hi,

i know this is a bit off topic, but i hope you can help me.

i'm trying to set authorities (update, insert, delete) for specific fields 
(columns) of a physical file. but the only way i found in IBM's information 
center (book: SC41-5612-02) was via a sql statement (like GRANT UPDATE(field 
[,field,...]) on library/file to user ). the problem is: this only works with 
UPDATE and not with INSERT or DELETE. i know that i could limit the access to 
the physical file by a logical file by one selecting the specific columns but 
that is not what i wanted. my goal was to write a GUI for that in java (mostly 
to get into the java thing connecting to the as400).

my question: is there any other way to set some authorities on the fields of a 
file on the DB2/400 (perhaps in the DDS of the physical file)?

thanx in advance