I don't think there are step-by-step instructions but Syph's descriptions tell it all: use a short 91mm inline Phillips and reshape the tang to match the 93mm openers (that's the hardest part). Then use two 93mm opener bacsprings in opposite orientations and add the appropriate spacers (in my experience 1mm and .5mm) next to the Phillips.
Would anyone have pictures of the Phillips after filing it?