You can create a linked server to the AS400 system and potetntially get to the data. I have not done this but you can look in the search area for AS400 and variations of it for a few threads. Also of note, unless you need to tie the data back to the SQL server in some way or have another special need. Then you really should do a direct connection to the AS400 not via SQL.
"Don't roll your eyes at me. I will tape them in place." (Teacher on Boston Public)