A ritualistic method for performing debasement training on a sub; likely most effective in a relationship where the sub is one who genuinely desires wearing and using diapers from the start. Also, this is not a method for those who are uninterested in severe humiliation/degradation games.
Prior to delving into the more extreme end of this training, it is important to learn how to bring your sub to climax while they are diapered. Discover and/or perfect this, and the following process will be much more effective.
***Developing a trigger for desperation
Have the sub avoid evacuation for a couple of days (this depending upon frequency of sub's normal activity). Once the sub has reached the end of the prior determined duration, give the sub approx 1/3 of a Fleet disposable enema and then diaper as per usual (perhaps with a bit more cream and powder). Have the sub hold the enema for as long as they can (typically no more than 5 to 10 min) and then decide an activity for them to do.
The activity becomes the point of attachment in the process-Pavlov's bell. If done regularly enough over a period of time, always with a predictable outcome, the sub will slowly find themselves reacting similarly when experiencing the activity even without the use of the enema. This can be interesting if the sub is made to perform the exercise without the accompaniment of a diaper. While it is not intended to cause true incontinence, it will make the sub feel the uncomfortable need to go-which won't abate until they do so.
***Growing the duration
Once the sub has soiled themselves, decide another activity for them to do. Easiest to conceive of are chores, some type of work; make them useful rather than just letting them sit (although a devious option that works well for a sub into pornography is to let them peruse the internet until their hearts content-but only pornographic content). In the beginning phases, shorter time length activities are best, then slowly work up from there (starting roughly in the 20-30 min range).
With plenty of attentive care and creams/lotions/powders in use, a properly trained sub can be made to go safely, albeit uncomfortably and ashamedly, for a full night in the same soiled diaper (mind the thinner ones, which will not last this long). Although, the most stoic sub will desire a change rather than remaining confined to their mess, which leaves them in an incredibly vulnerable state.
***Attaching the orgasm to escape
Now that the sub has been trained to eliminate somewhat on command, and has suffered remaining painfully long stays in a filthy diaper, the final debasement is attached to becoming free from this humiliating scenario. Like determining the length of time by activities that the sub will remain in their soiled diaper, whether or not the sub will be able to cum will determine whether or not he/she is changed. Once the sub reaches climax, reward them with a shower/bath, then followed by whatever is usual per your typical exchange.
It can be especially frustrating for a sub who is having difficulty achieving an orgasm, as their stay is based on whether they are able. This is where knowing how to make your sub cum in their diaper (the harder the better) becomes necessary. With the already present stress of the sub's predicament, he/she may have a much more difficult time reaching climax under these conditions. Having strong prior knowledge on how to bring them to a (powerful) orgasm will aid in shortening this time (although, watching them suffer through the stress and humiliation for a lengthier time can be quite rewarding in and of itself).
After instating these rituals into the sub's routine and practicing with enough regularity, the sub will eventually have developed a trigger for the urge to eliminate in response to a certain stimuli, and a strong link between being in a soiled diaper and experiencing strong climaxes. Surrounding the above details, there remains plenty of room for the imaginative and malicious.
I'd be curious to read results if any tops were to take this idea and make an attempt at it.