hi
I don't have any example to give you, but as a start point, I would look at setting up an ODBC connection to your AS400, so your going to need IBM AS400 Client Access Express.
This will give you access to the database files and read the files as a source and do your required ETL.
As far as marking it as flagged goes - it may be worth looking at implementing a stored procedure on the AS400 or some sort of macro, and passing and id to the sp or macro.
Hope that's useful to you.
_____________________________________________________________________________MCITP: Business Intelligence Developer (2005)