What methods do you know of for frequencies to be worked out, and then verified?

It's really quite complex. At least in terms of destroying pathogens. As far as the healing frequencies go, that's another story.
I suggest you read:
http://www.dnafrequencies.com/1999.shtml

This is a story of an exploration with numbers.

The origin of the MORs (Mortal Oscillatory Rates of bacteria and viruses), originally discovered by Royal Rife during the first half of the twentieth century, has perplexed many people since that time. While it is generally acknowledged that some type of resonance phenomenon destroyed or debilitated the organisms, it has been difficult at best to pinpoint any association of specific frequency with what is physically affecting these life forms during the time of their debilitation or demise.

What exactly might be the destructive mechanism that is affecting each organism? Is it a resonance related to its full size, or perhaps that of the nucleus, mitochondria, or capsid? Is it a correlation with some type of biochemical resonance? Why does each organism seem to need a specific frequency? Could the phenomenon be related to its DNA, and if so, what is the resonance relationship? These questions and more have kept folks that use or explore Rife-related technologies awake into the wee hours of the morning on many occasions, and have been the focus of endless animated discussions.

This paper will explore some possibilities that might assist in shedding light on the resonance relationships.

For more details, please check the link:
http://www.spooky2.com/forums/viewtopic.php?f=12&t=5317