Noise parameters describe how the noise of a circuit or a device depends on the source impedance. So, you will probably have to perform several simulations with different values of the source impedance in order to find the noise parameters. You could for example try to implement one of the methods mentioned in http://www.rohde-schwarz.com/WWW/Publicat.nsf/article/n153_fsm/$file/n153_fsm.pd... in your simulation.

One difficulty in modeling the noise in SPICE might be the partial correlation that usually exists between the two equivalent noise sources. It might be possible to realize this correlation by using a noise source together with controlled sources like vcvs and vccs but I have never tried this.