I can find discussions on the subject (Entering Maintenance Mode without switching headlights on/ off but not the instructions. What should I use in the search box?
Not sure, but looking through Repair Manual I'm only seeing Inspection Mode, no chicken-dance, and seems like you have to have Techstream?
If you read this thread you'll find what you're looking for, though I could be wrong. Entering Maintenance Mode (aka 12V Battery Check) without Switching Headlights ON/OFF | PriusChat
The mode that the OP is asking about, commonly referred to as maintenance mode, is not inspection mode. The procedure the OP is querying is done on the MFD. So this is just derailing information. Nothing. A) It has nothing to do with the question asked; and B) It is not applicable for Gen 2. It is also unhelpful posting what may seem like interesting things to you, but it derails the thread when it has no relevance to the subject matter. Please consider the subject matter, before posting. Incidentally, using the method that uses the light switch technique, it is not necessary to switch the headlight on/off, it is enough just to switch the side/marker lights on/off.
Now I will try to answer the actual question you've posed, I found the above posted thread which contains the instructions by searching for the first three words you initially posted about: "Entering Maintenance Mode" (without quotes), and limiting the search to only return results from the sub forum 'Gen 2 Prius Care, Maintenance and Troubleshooting'. When the results are sorted by 'Relevance', the first entry was the above thread. Were you only looking for the instructions contained in the first post of the thread titled "Entering Maintenance Mode (aka 12V Battery Check) without Switching Headlights ON/OFF", or were actually looking for additional help with using the builtin PriusChat search engine?