cnn.Open "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=A.mdb;Jet OLEDB:Database Password=aaa"
cnn.Execute "INSERT INTO [B.mdb;PWD=bbb].b SELECT * FROM a"
or
cnn.Open "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=B.mdb;Jet OLEDB:Database Password=bbb"
cnn.Execute "INSERT INTO b SELECT * FROM [A.mdb;PWD=aaa].a"