Kills you get from care packages don't count toward killstreaks. So why the emergency airdrop if you want a nuke?
It's quite simple although I haven't even tried to get it yet. My approach would be the same as others killstreak wise. Harrier to Chopper Gunner to Nuke. My weapon setup would be: M16 w/ Silencer or Preferred Sniper w/ Silencer M9 Raffica or Shotgun (M10 or Model 87, something with range) All Silenced Claymore Stun Perk 1: Scavenger Pro Perk 2: Cold Blooded Pro or Stopping Power if you're playing Reg Perk 3: Ninja Pro (Two reasons I like this one, some douche with heartbeat won't see you and you can sneak up being the guys that can actually hear footsteps.) If possible, it will be a lot easier to get it with a friend. Someone who will protect your camping area that you cannot protect. Obviously putting down 2 claymores is a must. Make sure your friend has something for close combat seeing how you're likely to hold up in a building, P90 and shotgun are good choices. The thing you gotta do is be completely silent, it's better to try this in Hardcore because of the killcams in regular. I hate killcams personally, then at times I love them. =P