Hmmm, interesting. I don't have experience with the CD-ROM version, but I imagine it's similar to trying for Ginjirotchi on a regular P1. You would have to get the healthy teen first (Marutchi) and then from there, take medium care of it. This might help as well: https://mimitchi.com/html/tamatip.htm. Of course, I could be completely off about this but that's how you would do it on the Tamagotchi. Good luck!