I think tulpas are more like schizophrenia than dissociative identity disorder. But now that you mention it, dissociative identity disorder does look like fertile ground for finding more munchkinly ideas.
For instance, at least one person I know has admitted to mentally pretending to be another person I know in order to be more extroverted. Maybe this could be combined with tulpas, say by visualizing/hallucinating that you're being possessed by a tulpa.
I've always pretended to be in order to get whatever skill I've needed. I just call it "putting on hats". I learned to dance by pretending to be a dancer, I learned to sing by pretending to be a singer. When I teach, I pretend to be a teacher, and when I lead I pretend to be a leader (these last two actually came a lot easier to me when I was teaching hooping than now when I'm teaching rationality stuffs, and I haven't really sat down to figure out why. I probably should though, because I am significantly better at when I can pretend to be it. And I highly value being better at these specific skills right now.)
I had always thought everyone did this, but now I see I might be generalizing from one example.
Thus spake Eliezer:
It seems that many here might have outlandish ideas for ways of improving our lives. For instance, a recent post advocated installing really bright lights as a way to boost alertness and productivity. We should not adopt such hacks into our dogma until we're pretty sure they work; however, one way of knowing whether a crazy idea works is to try implementing it, and you may have more ideas than you're planning to implement.
So: please post all such lifehack ideas! Even if you haven't tried them, even if they seem unlikely to work. Post them separately, unless some other way would be more appropriate. If you've tried some idea and it hasn't worked, it would be useful to post that too.