You can easily get all of the non-host only achievements in this game by hosting the game from another device (like a pc, tablet or a phone), which has an achievement world on that device. Assuming you've got a PC, download the game on that PC, open the achievement worlds mentioned in my walkthrough here and join that game with the apple tv. Minecraft (Windows) Walkthrough
Achievements currently known to be host only: (this might change over time when new updates come out)
- Diamonds to you
- Artificial selection
- Beam me up!
- Great view from up here