Hey Richard, welcome to the forum
I have your message on my browser since last week, and could not figure out how to help you. Here are some thoughts anyway.
Apparently, Dean Fertita does not use his Little Phatty in a guitar amp as with The Dead Weather. That being said, if you start from the album rather than from the youtube lives (which I obviously recommend), you may find that to be an intersting clue. You can use amp sims (I do it all the time...)
Misfit Love:
Quite simple solid bass patch. In the album, there seems to be a major third: I don't know whether it comes from the second oscillator or from some sync between them -the oscillators. Later on, there is a talk-box'y sound. Seeing this live, I guess it comes from the Phatty. Try to start from the original patch named "Throaty something" (it might be the #98 or so).
My god is the sun:
This one has no sustain, no or few filter mod, just a bit of triangle LFO to the pitch. The filter is rather closed. I guess Try Von Leeuwen is playing the second note as the two tones are not always separated by the same interval.
If I had a tail:
Classic Phatty sound. Try osc1 -> Square and progressively mix in the second one to get that character. An important point here is the filter envelope: you must find the right settings for the right shape, with little resonance.
Kalopsia:
The verse bass patch has no sustain and mid decay/release. Here again, the filter envelope will get you closer to the character you're looking for. Try little resonance, and try sawish waveforms.
Hope this will be a good starting point
