Hi,
as far as I am aware you do not need to update the firmware unless you are going to buy the latest V4 board (makes sense ) If you look at the last posts in this thread posted by me there is a set of instructions using the programming module you have listed. You may need to change the com port to the one your board picks. Upgrading OpenEVSE / EmonEVSE Controller Firmware using ISP programmer - Integrations / OpenEVSE - OpenEnergyMonitor Community after that it should be plug and play
John