Yes, as you have an RME UCX in your sig, just use TotalMix … configure a WDM device in the Hammerfall DSP Settings routed to the required outputs, then in TotalMix matrix (“M”) route it to the inputs you have configured in WaveLab. You could also just use RME DIGICheck’s Global Record function and load the recorded file into WaveLab.
But I have to ask, if you already have a “song” that you can play in Media Player, why not just load the file directly into WaveLab?