Over from HPMOR, and have been thinking about teaching exercises. Disclaimer: I haven't read all the comments, and apologize for any redundancy.
The two sources for exercises that I thought of first were CBT treatment for depression--as you mention briefly in the post, it turns out that overgeneralization about oneself is a big component of the disorder--and writing classes. Looking up the relevant CBT training suggests that it's actually quite similar to many writing exercises, which suggests that it also ought to generalize to your training. Unless that's overgeneralization. (Sorry.)
From Watkins, Baeyens, & Read (2009):
"In the initial training session, participants first worked through a 10-min guided relaxation procedure in which they practiced tensing and relaxing various parts of their body while focusing on their breathing and bodily sensations, designed to focus attention down to direct sensory experience and to improve concentration for the later exercises. Next, for the remaining 60–80 min of the training session, participants practiced the key elements of concrete processing via direct instructions, guiding questions, and using mental imagery: (a) focusing on sensory details in the moment (e.g., questions asking participants to focus on and describe what they could see, hear, feel); (b) noticing what is specific and distinctive about the context of the event; (c) noticing the process of how events and behaviors unfold (e.g., “imagine a movie of how events unfolded”); (d) generating detailed step-by-step plans of how to proceed from here. Guided by the experimenter, each participant practiced all these elements of concrete processing for six standardized scenarios (three negative, e.g., not being invited to socialize after work by colleagues; three positive, e.g., making new friends at a party) and for three personally relevant, self-generated, specific autobiographic memories (defined as memories that took place at a particular place and time and lasted less than 1 day; one negative, one positive, and one memory of an occasion when the participant was highly immersed and absorbed in the process of an activity because such “flow” experiences are characterized by concrete processing focused on the specific details of the task; Csikszentmihalyi, 2002).
...Thus, CNT included multiple elements all designed to encourage more concrete processing: sensory focus, mental imagery, recall of specific autobiographical memories, and explicit instructions to focus attention on experience, on distinctive details, on how events unfold, and on how to proceed (focus on “how” is a key element in theoretical conceptualizations of concrete processing; Trope & Liberman, 2003; Vallacher & Wegner, 1987)"
If I were adapting this for entrepreneurs with healthy egos, I would worry less about the valence of the scenarios and memories, and more about the content. For the standardized scenarios, I might tailor user cases based on the purpose of their start-up ("a single 43-year old man is sitting at his computer and has just encountered an ad for your matchmaking service; what does he do next?"). For the memories, I might ask for episodes related to the development of the business--tell me about the conversation in which you came up with this idea, tell me about a problem that almost derailed the whole thing... I would keep the flow memory--that seems like a great and still relevant idea. Focus on getting them to come up with clear sensory details--once you're imagining something that vividly, it's very difficult to describe a social network at a level where it could be both Facebook and Twitter.