Normally manufacturers of parts publish an entire SPICE file, so you don't need to extract parameters. This applies to devices like transistors, op-amps, etc.
Maybe motor manufacturers don't feel the need to do this, since usually a motor may be driven by relay and the major parameters are voltage and current, and you know it contains a coil, so you could simulate that at a very high level with just a resistor and an inductor. You could just look at an existing SPICE model for a motor, and guess what the parameters are (it is fairly intuitive, it uses node numbers and component names/values). For example by observing the built-in model in Multisim you can see that is an inductor
(1mH) and a resistor (2 ohm) in series. If you wanted to create your own from scratch and not copy an existing model, then you'd
need to understand the SPICE format and what the contents mean.**broken link removed** contains details of the circuit elements (components) and
the syntax. **broken link removed**tells you the overall outline of the file contents. I think it is easier to understand if you just look at some existing SPICE models in your simulator first, to get an idea of the content.