If anyone wants it, here's a guide on how to become leader when you still look like a kit.
1. Use the pelt color that's gray with a brown ear. Then, make yourself female and name yourself Sliverkit. (I read about this in a comment further down)
2. While you are still a kit, go around getting the blue gem (In the tree by Amberclaw; click on the owl, then the gem), the white gem (go to the tiny stream and slip/fall in it), and the yellow gem (Go to the beach) to save yourself some time.
3. When you become an apprentice, you'll find that you automatically have 222 rep. and health because of step #1. Defeat the badger @ the hunting grounds and get the green gem (talk to nightpaw).
4. Once you've done that, talk to Hollypelt and she'll make you a warrior.
5. Once you're a warrior:
1st, talk to Milkywillow so she'll move into the old badger den.
2nd, talk to Moonheart to learn about Mosskit.
3rd, go to the warriors' den, grab the moss ball Darkclaw used to throw, and then put it on the X at the beach. At moonhigh, Mosskit will be there. Escort her to Bramblestar.
6. Due to your large amount of reputation, Bramblestar will make you leader on the spot. After he does this, talk to Liontail (Yellow guy in the Elders' den) and he'll give you the final gem.
7. Go to the Cold Stone, receive your nine lives, and congratulations! You're the youngest leader ever!
Hope this was helpful. =)