The Dork Knight himself.
Not entirely sure if this will work, but I'd say strip the audio from the file, then change the playback rate for the video (not convert, just change it) to 29.97, then re-mux the audio back in.
***Edit***
I re-read through this topic, and you did mention that you're using a y-splitter to get the audio to your soundcard. When you were using Amarec, did you try just plugging your console directly into the Dazzle and selecting Dazzle Audio when setting up Amarec or did that still cause a desync?
Another thing, if you want to use the Amarec + VDub combo, just completely disable the deinterlacer on the Preview tab and set the Live output to 30fps so it will send the raw interlaced footage to VDub (don't know why I didn't think of this before).
***Edit***
I re-read through this topic, and you did mention that you're using a y-splitter to get the audio to your soundcard. When you were using Amarec, did you try just plugging your console directly into the Dazzle and selecting Dazzle Audio when setting up Amarec or did that still cause a desync?
Another thing, if you want to use the Amarec + VDub combo, just completely disable the deinterlacer on the Preview tab and set the Live output to 30fps so it will send the raw interlaced footage to VDub (don't know why I didn't think of this before).