Frank is right. QPSS is the way to go for the base analysis, with QPAC, QPXF, and QPnoise being used for the various small signal analyses.
You will also want to take a look at
Accurate and rapid measurement of IP2 and IP3 at
http://www.designers-guide.com/Analysis/. It describes a way of computing
IP3 that is much faster than the traditional approach. That paper describes the technique in terms of an LNA and PSS/PAC, so you will have to adjust the procedure to fit a mixer and QPSS/QPAC.
-Ken