well that depends in what context you are putting it in. in a private match you simply create a private match and invite whoever you want to be with. in online matches it is a bit random as when host migration happens. they will choose whoever is the best host from those who are playing those matches. so if you have the best connection out of all of them then you will be host :P
You can't choose to host it. the game decides host based on connections.
get there first and be on the same team as the other people
how should i know i wanted to know that's why i typed in the question
Huh? Modern Warfare 2 is a game, not a category.
Buy a Connection!
You have to get invited by a co-host or a host that hosts challenge lobbies
no
You need a JTAG.
No patched
It has to be some Call of Duty game...my guess is either Modern Warfare or Modern Warfare 2
you can find a list of achievements at: http://www.xbox360achievements.org/game/call-of-duty-modern-warfare-2/achievements/ and also a guide for them at:http://www.xbox360achievements.org/game/call-of-duty-modern-warfare-2/guide/
You cannot on live because that is how it is programmed. But on private you can host.