Here are my B3 settings that I used for Plug In Baby. And before I get shot down in flames for not getting it spot on and exactly like the original, I know. But, through my rig, my bass, my board and with my fingers, it was close enough for blues on the night. And it sounded great in my opinion. I didn't use an octave, but it wouldn't hurt to put one on if your normal tone is quite mid focused or twangy. Mine is fat and bassy to start with so I left the octave out. Hopefully this will be a starting point that you can tweak to suit your gear.
Effect1 - Bass Muff. Gain-55, Tone-75, Level-90, Mode-BassBoost, Balance-25.
Effect2 - M Filter. Freq-84, Sens-4, Res-5, Type-LPF, Char-2 Pole, Vel-Fast.
Effect3 - Graphic EQ, adjust as necessary.
I hope this is of some help.