Similarly to the BemaniPC, a keepwarm voltage is generated by 9 resistors on the power distribution board. They are labeled R61,R62,R63, R65,R66,R67, R69,R70,R71
Unfortunately you cannot bypass the power distribution board with the python as a shift register is used to encode/decode lamp data rather than individual pins.
You can still desolder the resistors to perform the LED mod.