MS ole db provider for db2 requires Enterprise edition of sql.

..and I believe for you to obtain IBM IseriesClientAccess software from IBM site, you'll need IBM userid/password if you are entitled for a software support.

I use both Iseries Client access and oledb provider for db2 and either works pretty well. Our production servers use the ClientAccess on our ssis packages to ETL between SQL and as400.

My client machine has developer edition of sql, so I use MS oledb to connect to iseries through linked server.