I suppose that Mike @Engelhardt was referring to the Winslow Impedance Probe, which is not quite the same as the .net directive, but can also be pretty useful. For simulating the S-parameters of a circuit directly, I would also recommend the setup shown in Figure 25 of https://designers-guide.org/forum/Attachments/CreateS-ParameterSUBCKTinPSpice.pdf.