if you haven't already i recommend reading through these LSJ Guides <-- Link
The 10% method takes a while to explain. It operates off the basic principle that if you command additional 10% fuel then the AFR Error or Trim Error should report back that the engine is 10% rich. If it reports anything else, then the base injector data values are incorrect.
I don't have a ton of time to write the instructions flat out again. Attached you will find the document that i used to develop my tuning method for unknown rate injectors. It's the best i can offer you with my limited availability.
As i said before, its best to send your units out for testing and getting the characterization data back in return.
Disclaimer - Use the information at your own risk. If you don't understand fuel injector operation, injector flow dynamics, or the how the ecu controls for linear and non-linear flow zones, this method will cause major damage.