I created this video as part of a research project when I created a new twin plug solution for the 3.2L engines. This video gives you a decent idea of what it takes to gather dwell time data on a test bench with custom circuitry:
https://www.youtube.com/watch?v=a7dFdIdsZeU
Once you gather this data for a given coil you then need to alter the dwell map in the DME with the new data.