Editing config files which are not in database directory

Debian server standard installation places pg_hba.conf, pg_ident.conf, 
postgresql.conf , start.conf files to  /etc/postgresql/8.3/data
Database cluster is in /var/lib/postgresql/8.3/data

Trying to edit pg_hba.conf  and postgresql.conf  from pgAdmin 1.10.0 from 
windows causes errors and shows empty file:

ERROR:  absolute path not allowed
CONTEXT:  SQL function "pg_file_length" statement 1
STATEMENT:  SELECT pg_file_read('/etc/postgresql/8.3/data/pg_hba.conf', 0, 
pg_file_length('/etc/postgresql/8.3/data/pg_hba.conf'))

ERROR:  could not stat file "postgresql.conf": No such file or directory
CONTEXT:  SQL function "pg_file_length" statement 1STATEMENT:  SELECT pg_file_read('postgresql.conf', 0, 
pg_file_length('postgresql.conf'))

How to edit conf files from pgAdmin in this case?

Andrus.