The above checklist is pretty good but no-one is going to write a comprehensive and approved checklist that goes beyond what is already there.
Turning the utilities off kills domestic services in the cabin but that's about all. There's a cabin crew back there who are trained to deal with fires and they should be working on it. If you're convinced the source is electrical, my advice would be to turn off one generator to see if that stops the smoke, if not then the other. Since an electrical fire is a symptom of overload or short circuit, loss of particular services or equipment is a good clue as to the affected system(s) Ultimately, if you're CERTAIN that its an electrical fire but can't figure out where, start the APU while the battery (or batteries depending on configuration) is/are still fully charged, kill all electrics (except the "Hot Bus" which you can't kill anyway) and try to find the source. (Just in case its the hot bus that's responsible, its behind the F/O at the bottom of P61, but I reckon you'd have no problem sussing that out if it was on fire!). You've got at least 30 minutes of emergency power while you hunt for the fire. Remember there is access to the MEC through a hatch in the floor just inside door 1 Left. You may have to take up the floor covering but that will be lose - maintenance use it frequently. Once you know the source you can isolate the affected system and restore electrical power.
It seems to me that this is not a situation for both pilots to be sitting in their seats running through a checklist. The infinite permutations of where and what could be causing the smoke don't allow for that.
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Through difficulties to the cinema
[ 08 August 2001: Message edited by: Blacksheep ]