I think you would have to do it manually, by de-pboing the mission, opening it up in the editor, and replacing all the units. The re-pboing it and make it back into a campaign.
You could also make your own mini conversion mod, but I have no idea how to do that.
Prehaps what would be easier if you have a good enough connection would be to download a conversion mod. I think FFUR 2006 has an option to use ACU soldiers. It also replaces just about everything else with new models, and has great effects. http://ofp.gamepark.cz/index.php?showthis=9632