There's more to it than just a low pass filter. The pickup's inductance causes resonance in the circuit, so there are resonant peaks in the response that change as you roll the tone control down. With the Tone on 10, the pickup's resonant peak is prominent and you have the least treble loss. With the tone in the middle range of about 6 through 4, both resonant peaks are fairly leveled out. With the Tone at 0, the filter's resonant peak is prominent at the cutoff frequency instead and you have the most treble loss.
The location of those cutoff and resonant peak frequencies depends on not only the pickups, pots, and capacitors in the guitar circuit, but also the capacitance and impedance of the cable and receiving input as well. You'd need to no only simulate the changing cutoff and resonance of the filter, but also the changing resonant peak of the pickup as well. It's doable, but not easily.