[DoIFeelLucky]

You may need some kind of wav editor to cut/add silence to your lossless source as well, cause I'm sure it will be of different length from the DVD video (Murphy's Law, pretty much).

You'll need something to rip the DVD, (DVD Decrypter is great) and then demux the video. Then you'd need something to mux new VOB files using the demuxed video your own audio from the lossless source (I'm assuming you'll want to convert it to uncompressed LPCM @ 48kHz).

I don't have much experience with DVD creation software... I think that IfoEdit can handle the re-muxing, but you'll have to look around for guides.