You can in HALO 1 if you use mods, but it has to be on the computer.
If You Mean change into elite, no, you can only do that in Halo 2, 3 and Halo Reach. But however you can use mods at halomods.com
You are not able to at all without the use of mods.
its easy download it at filefront.com copy this where halo trial halo 1 halo 2 halo 3 mod mods ok?
sorry but other than mods you can't "cheat". you can use as many guides and tips as you like!
You can't unless you use mods.
You can mod halo 2 on the computer by enabling some mods downloaded from halomaps.org, or you can make your own using those tools.
depends on what you're looking for. but most good mods in halo require a jtag. but a good site to look up mods is- http://www.thetechgame.com/
Mods.... search halo armour oblivion
As of now the Halo: Reach beta is gone, your not going to be able to.
Yes. There are a lot of mods for Halo and Halo Trail on PC.
See halomaps.org for mods like sonic for halo. It is only for Halo Custom Edition, but you can convert it to Trial or Retail with Pearl or Demo with Queene Anne's Revenge.