If you do it with avisynth, you got the command:
trim(xxxx,yyyy)
But how do you find out "where" to cut?
Easy .... do load that "d2v" via "load source via avisynth" and so set there the right decoder "mpeg2dec" in the open window message requester.
Now you got the video in Vdub mod. Do your cuts as known from VDubs editing functions.
THEN do go into "script editor" above to the right in the window bar menue.
Now you see your avs script. Go with your cursor below the import line and choose from the edit menue "import framesets as trims" and *pong* the right trim commands will be insertet - ready. Use "safe" and the generated avs in the same folder like the orig d2v is updated in its added trims
You also could do that using the cutting function in DVD2avi but that would result in a fix cuttet d2v where in other workout when using Vdubmods avisynth section you easely can inverse wrong trims or if you find a different/better scene you want to trim
BUT! A direct fitting/cutting of the untouched original mpeg/vob would be more economic as theres no need to reencode. AND if that orig cuttet mpeg/vob via that tmpgenc editor/cutter does result in too much filesize, you can pre-treaten it by using "Rejig" to get a less filesized motionmenue footage before importing in your DVD project
as "rejig" supports mpeg2 files directly.
Thats also an option which (IMHO) should be available in DVD-RB as it leaves the VTS_0.VOB incl. the menue intact by just re-merging it. As a simple transcoding of a big orig motionmenue would make sense anyway IMHO.