You basically layer the bad aspects of the disintegration point, and mix them together with your type. You don't "become" like your disentegration point, but simply mirror it.
In my case, when I am disintegrated to E4, I will more frequently become more condemning, harsh, and rigid with other people and have no tolerance for deviance of any kind. In order to stop it, I will somehow "create" objective facts that have started from personal opinion. The latter of which comes from E4. This is done because for an E1 anything that even smells like it's source is personal and from the self is NOT ok, so the most convoluted or twisted logic will emerge to prevent the individual from even realizing it's the case. Another thing E1's who have heavily disentegrated will attempt to do is steal or block the voice of personal opinions of others. This is something E4's would never strive to do, but when it's mixed in with E1 that's exactly what it becomes. Another common theme for E4 disintegration is being immensely self critical, self punishing, and self restrictive. Often, it will be completely lost on the E1 the extent that this is being done, or even done at all.
Looking at integration/disintegration points is IMO one of the biggest key's to figuring out ones enneatype. I have a lot of qualities of 3 (not obvious to others) and 6 (obvious to others) that can and do lead people wondering if that's my true type. Nevertheless, I neither evolve, nor devolve to E9 (I don't relate to E9 even slightly, and becoming E9-like would be profoundly counter-productive for me). However, I do evolve to E7 (occasionally toxicly- it's possible for someone to integrate poorly), and dissolve to E4, which clinches it.