There are a few options for getting testing data into the base dataset. KFS has used a few different methods over its development cycle. I'll try to list out some options. They are not mutually exclusive.
Part of this will involve updating the master datasource. More on that is described in OLE Database Management Process. But, I will refer to that master datasource here as OLEDBA. (Happens to be the name of the Oracle database schema.)
Option 1 - Update OLEDBA Directly
At any time, you can request that data be added to the master data source. Any database changes made to that schema will be exported into version control and then imported into the test environments when their databases are reloaded.
This option requires that you know in advance what tables need to be updated and how to load the data properly for the system functionality.