Yes is possible to do this test.
One option, but very expensive is to use a RF Probe Station like this: http://bridgetec.com/rf.html
Second option is to de-embed all the PCB losses between board connector and the pin that you are looking to measure, and do the characterization using a Vector Network Analyzer (VNA). This de-embedding and calibration of the VNA require some RF experience
You can search on the net for some examples like this:
**broken link removed**