It's not hard. Lots of inking and drybrushing. I use a flat head paint brush.
The IC horses: I use various paint companies, mostly Valejo Model Colour
Intense Blue over all the barding.
Andrea Blue on most of the surfaces, leave recesses in the armour and don't paint the ridges of the armour
Game Colour Blue Ink the entire thing.
Andrea Blue painted on the armour plating leaving the ridges of the armour and the joins of the armour (the ink just adds a depth of colour missing). Don't paint the areas going to gold.
Highlight with Sky Blue.
Paint the Gold areas with Brass (gold won't work on the blue as I found out). Paint over the Brass with Gold. Ink the Gold with a 1:1 Chestnut Ink:Brown Ink mixed with 50% water- do not let it pool just shade the gold.
Paint a black line around the gold and neck plates.
1 thing I need to add is a coat of Natural Silver highly on the gold plates.
The red is even easier!
Mechrite Red (GW paint) Dry brush Flat Red. Ink with a 2:1 Game Colour Red Ink: Game Colour Blue Ink mix with 30% water. Depending on the blue added you get a deep burgundy/purple colour. I love it. Ink the models!
Dry Brush Flat Red or Carmine Red (Carmine is a little lighter).
Highlight with Fiery Orange (or GW Blazing Orange)
Ink with Game Colour Red Ink.
The red horses are the same as above but with the gold steps from the horse.
In this manor I was able to do them all quickly.