Yes, it will work on Zener modded drivers.
These are the threads I used to learn to flash FW:
Guide: how to flash ATtiny13a based drivers (NANJG, QLITE, etc.) with custom firmware
howto: Use Atmel AVR Studio 5 to make a .hex file
Flashlight Firmware Repository
Crescendo is currently located here: ~toykeeper/flashlight-firmware/sandbox : files for revision 185