I don't know the best way to get into the heart rooms, but I can tell you how I did it.
From the first time I stepped into a heart room, I knew that was what I wanted to do. And I made that loud and clear. I let anyone, and everyone, know how much I loved hearts. I would hold heart until I thought my arm was going to fall off, and I'd keep smiling because I was in the heart room. I let the heart surgeons (some of them are satan, I swear!) yell and scream, but I kept on going, telling anyone and anyone how much I loved hearts all the while. I ran, not walked, to the heart room any chance I got. I took all the ridicule and scorn about "those snobby heart team people" and kept smiling, and being friendly, and willing to do just about anything else, although everyone knew I'd rather be in the heart room.
It worked for me. Maybe it will work for you too. Just be ready for the "why would you want to do that"s and the "I wouldn't do that, I want a life"s. Just brush them off and keep going, because you know what you want.