Can you disable pop up flash when using DTTL to trigger speedlight?

I have a Nikon D100 and I'm trying to use the D-TTL system to trigger my off camera speed light. I only want the speed light to flash and not the pop up flash. Is there a way that I can still use the D-TTL and disable my pop up flash? I'm using a SB-50dx.

No. You would have to buy a commander to put in the hot shoe, with a commander you can use multiple flashes, but they are kind of expensive. I made a little cover to put over my pop up so it diffuse the light, but can still see the flash.