The technique is based on the core device models of SPICE and adds a controllable flicker noise component to white noise. The resulting “macro” is inserted into a circuit as a circuit element.
This is a method I’ve used long enough that I’ve forgotten which decade I first applied it. My earliest reference is from the 1980s; the origin is lost in the mists of time … school?, colleague?, original thought? In any case, it’s served me well.