No.
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.
unless your using a mod you cant
It matters how you mod it, if you just get a mod from "Modio" then you would be using the account that you moved to your computer, it just matters what account your using. If its a online or offline account. If your not familiar with Modio you should it up. Its a great program!
Yes, you can mod campaign mod on the Halo trial.
If you are using the PC version you can use a program called halo custom edition, just type it into Google. Unfortunately there is no easy way to mod on a console.
There isn't a way to mod Halo for the XBox. You'll need the actual computer game to do this. Yes you can mod halo for the Xbox but you need an action replay memory card and the original Splinter Cell game and that's basically all I know just google it and you'll find something on how to do it. You will need special tools found in off color irc channels. You will also need, as was stated by previous person, a modified XBOX, but, it can be done both the way suggested or using what is known as a Mod Chip.
no there is no mod to become Jorge in any Halo, I wish there was to be honest with you :]
There is no Halo 3 mod for Halo Trial. Halo Trial is one of the hardest versions of Halo to mod. There are however, custom maps for Halo Custom Edition. To get Halo Custom Edition, you need to have Halo: Combat Evolved installed on your PC, you also need your CD key. You can download Halo: Custom Edition free.
i dont think you ever can without a mod atleast in story mode
No, not without a mod. But you can in the custom games when playing single player.
you can get grunt mods for halo trial but not halo pc. If you want a grunt mod for halo pc, then you will need to mod it yourself with HMT v3.5, Spark edit v3.02, and/or HHT v5.
it's ileagal to be a mod you idiot