In "A Thousand Sons" the Legion uses the enumerations to control their psychic power, emotions and their rituals. I see it as a descending spiral moving deeper into the immaterial while still linked to their mortal form. To put this into Black Crusade I see it has a series of talents that makes using Psychic Powers easier but at the cost of awareness of the Material world around them. A very basic outline of what I have in mind. If anyone has used this idea before I would like helpful tips. One of the PCs in my game is a Sorcerer that has recently become dedicated to Tzeentch. I am thinking that the character can only be within one enumeration at a time which lasts for a given combat encounter if applicable.
There are many enumerations mentioned in "A Thousand Sons" and I believe Talents would be the best way to go about them. I have three of them so far.
The First Enumeration: It is taught in the earliest mastery of the warp and psychic power. By entering the first enumeration before a ritual it takes twice as long to complete but all rolls to complete the ritual improve in difficulty by one step (very hard becomes hard for example).
The Second Enumeration: Emotion can influence the nature of the warp and the power that is manifested within it. While within the second enumeration the character rolls twice on the Psychic Phenomenon choosing whatever roll he desires. Though if Perils of the Warp comes up that must be selected as his emotions rage out of control it adds +10 to the result of Perils of the Warp.
The Third Enumeration: Building upon the lessons of the First and Second Enumerations to allow the Sorcerer/Psyker to count the penalty of pushing has being half the amount (rounded up), though the next turn their actions would be limited to one half action. This action can be used in combat.