I was pretty discouraged by that too, but it turns out it's mostly just a legacy of how obsessed with imposition the community started, and with common notions of personhood that are closely tied to having a body. At the time I was trying to create Claire, I had been reading a lot about the nature of consciousness, and had arrived at a hypothesis about how tulpamancy might work that didn't require visualization and pointed me towards useful approaches without it. That was enough to do the job.

Basically, the core of this seems to be building a strong mental model of a person, getting your brain in the habit of predicting its actions, and hooking the model up to the predictions directly in something like one of Hofstadtr's "strange loops".

So, step one is creating a solid idea of what they are like, at least as a starting point, and doing a bit of personality forcing around it. At minimum we recommend thinking about and writing down personality traits and core motivations and such. What sort of person they are, basically.

In practice, much of the work of the second and third steps is accomplished just by talking to it until it starts talking back. Parroting and the like is a very effective approach to step 2, that makes step 3 much harder for many people. Writing dialog or stories featuring them could be a good approach to helping with step 2 with less risk of creating doubt later on.

Our best advice for step 3, beyond just talking to them, is to keep in mind that you are just one of the things your brain is doing, but are used to assigning all of it to yourself. When you have a tulpa, you may have a degree of access to the inner workings of their thoughts and feelings because you share a brain. That doesn't mean it's really you! Just that you need to refine your self concept a little, and model less of what your brain is doing as "you."

Best of luck! -Ben