Dont know why it should not work with Steam version.Sorian AI (2.1.2), official page:It specifically lists steam as one of the compatible versions.You just need to also install the lobby enhancement mod (same page) to be able to pick the AI's.I think that the difference is that on FAF they have those enhancements already built in and dont need that separate menumod.Total Mayhem (1.20), plenty of sites for that. Gogo google it. Be ready to adjust your soundvolume, the some of new sounds are on the loud side. If the file is called TotalMayhem120.zip you have likely found it.

Sorry if the answer is obvious but right now I am playing the campaign with modded units from mods such as total mayhem and experimental wars. I also want to use units from the blackops and extreme wars mods but I don't know if my modded campaign mod will work with forged alliance forever and total mayhem does not work with FaF. BrewLAN is a mod for Supreme Commander: Forged Alliance that has been in on and off development by a team of one for almost a decade.