1st - Import 2,000,000 Soviet soldiers. Men immune to misery, because it it their daily bread. Men who will willingly fight to the last breath to defend their Motherland (Rodina). Men who actually perfer to fight in basements in the pitch dark, because its warm. Make them think they are in Russia.
2nd - Import the NKVD. No, the sorry bunch of thugs that Saddam had on hand is worthless, Soviet soldiers wopuld have kept them as pets.
3rd - import Russian weather.
4th - Eliminate PMGs, all the way back to the early TV guided bomb.
5th - Eliminate the Heavy Bomber (from B-29 forward)
6th - Eliminate the Jet fighter-bomber
7th - Eliminate the M1A1, TOW missile, Bradly Fighting Vehicle, and Humvee with 40mm grenade launcher
8th - Eliminate the Assault rifle
9th - Eliminate every person who graduated from a U.S. or UK Service Academy since 1925 (just to be sure you got them all). every person who ever attended any staff college, VMI, and most military boarding schools.
10th - Replace the civilian leadership of the U.S. and UK with week old kittens.
Baghdad can now hold like Stalingrad, at least until the Israelis, Iranians, Italians, Indonesians, or Indians (just to use the "I" countries) show up with two mechanized brigades and a fighter bomber wing. The defenders will then be blown to hell with rapidity and massed firepower.