Hello,
here's a patch I found that cope pretty well the VT Bass vibe (not exactly the same but not very far as I hear it - if my ears are good, don't know

) :
VT Bass Sim
1- SVT : Bass : 0 - Mid : 0 - Treble : 5 - Gain : 69 - Level : 38 - Ultra : Off - Cab : Orgn - Mix : 38
2- AcBsPre : Gain : 50 - Depth : 8 - Level : 100 - L-mid : 0 (4 to simulate the VT Bass mids placed facing the Character knob)- LM-F : 1.2 kHz - Mid : 0 - H-Mid : 2 - Treble : -10
This sounds as my
VT bass V2 set with :
Mids : 12 o'clock
Character : 10:30
Drive : 12 o'clock
Bass : just below 12 o'clock
Highs : 11 o'clock
And with the
speaker sim non engaged (just for those who don't know, even with the speaker sim non engaged on the VT Bass V2, there's a cut of the ultra lows and and a cut after 5kHZ, the difference when the speaker sim is engaged is a big boost of the trebles and a light cut of the mids).
I didn't spend much time experimenting, so I don't know how to set this patch to simulate different settings of the Character knob.
Bass and Treble have to be set on the SVT sim, Mids with the AcBsPre L-Mid (they act on a large band, as the mids of the VT, when the mids of the SVT sim act on a very narrow band - more useful to cut some nasty tones I feel than to boost some mids).
You may say : "hey why not just use the B3 SVT sim alone, the VT Bass is also a SVT sim ?" .
The fact is that, what is tonally caracteristic of the VT Bass is the cut of ultra lows and of the highs after 5 kHz. And with the SVT sim of the B3 only, the only way to get these same kinds of cuts is to engage fully the Cab Sim. And there, it doesn't sound at all as the VT Bass. The SVT cab sim of the B3 is very scooped (kind of Bass Driver tone), so it gives something less flexible.
The VT Bass has a flatter response which is why mid lovers tend to like it.
So, the AcBsPre as I set it, acts as a smoother speaker sim, more in the VT Bass way. Decrease the Depth value if the result in your bass rig sounds too full of lows.