Alright you just need to know a few things about button binds to get this to work.
Take your gamesave, and put it in the Mw2 gamesave editor in modio. Go to the custom
and add the Dvar "dcburning;bind BUTTON_BACK vstr mods1;" without the ". This also needs to be a gamesave ready for online spec ops mods. When you go to the single player menu, and hit resume game press select in game then save and quit. Go to spec ops-Two player online-choose any set-and press the b button till your at the checkerboard menu. Here you can invite your friend, and It will be the campain. Most of the campain levels wont work but the one in the following gamesave will.
It also comes with
godmode(left)
Noclipp(up)
Dubug console(left)
Chrome(down)

There will be a video of this in action on my youtube tommarow @
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Premodded game save:
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