Toroidal Coil on OrCad Pspice
Use two inductors with appropriate inductances (proportional to the number of turns squared). Define a coupling factor between them (an ideal tapped inductor would have K = 1). If you know the leakage inductance you can calculate the non-ideal coupling factor (K &lt; 1). You can also include the winding resistance and even some parasitic capacitance.  

The appropriate part is TFRM_LINEAR in the analog library. 

However that simple model won't likely work for you in this particular case- this circuit depends on the transformer saturating so you'd have to find a nonlinear model including core saturation to get the oscillator to simulate.