You don't actually have to change anything. I've done plenty of four person drafts with 3 packs of 15 cards, and it works.
Deck quality is less than in 8-person pods, but it's the same standard for each player, so it balances. The main thing is that you need to keep a close eye on available colors. If three people are in black and nobody is in white, you generally do best to abandon black in favor of white, even if your first pick was a great black card. You'll start to notice the trends as the packs keep coming back.
But all the other suggestions people have made are great too. See what your playgroup is willing to try, and what they like to do.
Deck quality is less than in 8-person pods, but it's the same standard for each player, so it balances. The main thing is that you need to keep a close eye on available colors. If three people are in black and nobody is in white, you generally do best to abandon black in favor of white, even if your first pick was a great black card. You'll start to notice the trends as the packs keep coming back.
But all the other suggestions people have made are great too. See what your playgroup is willing to try, and what they like to do.
Low-power cube enthusiast!
My 1570 card cube (no longer updated)
My 415 Peasant+ Artifact and Enchantment Cube
Ever-Expanding "Just throw it in" cube.