Those app notes are all for mixers, where it is much easier to test port match or VSWR since the IF and RF frequencies are offset from the LO. However, for multipliers, there is no offset and it becomes more of a large-signal load pull situation rather than a small-signal VSWR. I don't know if we have app notes specifically for multiplier measurements.
Why do you need to specify or measure output VSWR for your multiplier?
AN1287-7 Improving NA Measurements of Frequency Translating Devices:
http://cp.literature.agilent.com/litweb ... -3318E.pdf
AN1463-6 (ENA) Accurate Mixer Measurements using Frequency Offset Mode:
http://cp.literature.agilent.com/litweb ... 1420EN.pdf
AN8753-2 Mixer Measurements using the 8753:
http://cp.literature.agilent.com/litweb ... 6-4362.pdf
AN345-2 Mixer Measurements using a Scalar Network Analyzer
http://cp.literature.agilent.com/litweb ... 4-8369.pdf