How are you going to be adding the condition that controls the data provider ?
A simple way would be to pass the toggling mechanism via a JVM argument which your data provider can query and then pass the respect file.
The "@DataProvider" annotated method can also accept an "ITestContext" object. So you could have this dynamic behaviour built by passing in parameters as well from your suite xml, which can be read via the ITestContext object in your TestNG data provider.
Thanks & Regards
Krishnan Mahadevan
"All the desirable things in life are either illegal, expensive, fattening or in love with someone else!"
My Scribblings @ http://wakened-cognition.blogspot.com/