The way to do it in Wavelab 6 was with the Cube-Tec DDP add-on.
https://www.cube-tec.com/en-uk/products/audio/ddp-solution-30/overview
I doubt they sell it anymore and it was quite expensive (>$1000 ?). It also required a separate dongle.
It would be much cheaper to buy the Wavelab 9 Pro upgrade from Wavelab 6. That would give you built in DDP and a lot more.
http://www.steinberg.net/en/shop/buy_product/product/wavelab-pro-9.html
The cheapest option is to render WAV/CUE or burn a CD in Wavelab 6 and find a program to make DDP from that. But I don’t think it’s worth the hassle when you can get an upgrade to WL9 for a reasonable price.