you can use
select * from yourtable where last_modified >=sysdate - 7
as a datasource
(provided that your source database is Oracle and you want to load data changed during last 7 days)
Than set transformation type to Add new and update old records
as described here
www.dbsoftlab.com/Documentation/Add-New-...xisting-Records.html
I am writing an article which describes the ways of synchronizing data between different databases.
When it is ready I will let you know
John