did mine after being inspired by vortexracing's post. thanks vortexracing!
i used the triple xpg kit from cutter, which includes the 3 led pcb and the b2flex driver.
vortex kindly sent me a drawing of the insert he machined but some dimensions were off for my housing - think these went through a couple of iterations, so you'll need to check the ID of the Lumi Head unit you have before machining yours.
other points to note:
you can bond the LED board to your heatsink if you want to, but i just drilled through the PCB ( keeping away from the tracks! ), and screwed the thing down with some heatsink jizz under.
the flex driver is on a later version and the instructions for it are not specific for the version number, but don't worry about it - it all works the same ( or seems to ).
snip down the legs of the optic to fit the 'shoulders' down to the LED pcb ( you'll see what this means when you get it ).
the instructions for programming the driver don't read terribly well IMO. just make a list of the features you think you want, and then you can look up how to get there with the button pushes, and write this out too.
if you're using a nimh battery pack you'll want to change the cut-off voltage setting on the driver, which by default is setup for li-ion. as i found out the other night when i used a spare nimh instead of my li-ion pack for the first time.
i'm going to set 1V per cell, which for a lumi pack is 11.0. you can apparently go as low as 0.8V per cell but i have plenty of capacity for the rides i do and want to keep the pack going for as long as i can.
i'm really pleased with the results. i'm running 3 levels, with 1500mA the highest, which i just flick on for fast downhill bits, then shut down again, as i haven't yet bothered to heatsink the driver and i don't want it getting too hot. when i get around to it i'll crack it all open and bond the diver in place with some more metal to heatsink it.
it's a very worthwhile conversion. good luck.