Step fermentation is what DFH does with 120 and Utopias. Small base malt and dextrose additions in combination with more nutrients and pure O2 additions. The principle is to keep the active fermentation going... and going.... and going.....
I know the 120 regimen takes well over a month of daily supplemental sugar and O2 feedings.
Another possibility is to do a rum wash, which is to brew both the base beer and distill some rum (yeah, illegal as hell without the proper licensing) and then blend the two together. Seems lazy to me.
Beer so good, it's frightening.
2014: Seven Heavens Series One: Vilon, Mystic Melomel, Skeeter Pee.