I got a bit of post-game depression, as all the main characters from the story line had disappeared from the world.
So I looked for a companion mod, and found one here?, however it didn't work, and I got a few errors.
Having some experience with programming, I went and found the original Witcher source files which the mod overwrites, and then re-modified them with the modded code, and voila, it works again!

And then I thought: I can make this better. I want multiple companions!
And multiple companions we shall have.

Commands:
SpawnCompanion(name, optional count, optional wantHUD, optional wantImmortal, optional tag)
Spawns a companion.
name: The name of the companion. Some companions are useless, they just follow you. Tested names include:
Ciri
Triss
Yennefer
CKid (Useless)
Lambert
Eskel
Ves
Roach
Uma (Useless)
Hjalmar (Useless)
Cerys (Useless)
Baron (Useless)
Dandelion
Letho
DemonWitcher (I don't even know what this is?)
wantHud: A 1(true) or a 0(false). Enables/Disables the showing of the companions health bar on the HUD.
wantImmortal: A 1(true) or a 0(false). When enabled make the companion immortal.
tag: A 1(true) or a 0(false). When enabled the companion has some text above their head which indicates their health, and distance from you.
Example Usage:
SpawnCompanion(ciri)?Spawns Ciri
SpawnCompanion(ciri, 10)?Spawns 10 Ciri's
SpawnCompanion(yennefer, 2, 1)?Spawns 2 Yennefers. The last one spawned is shown on the HUD.
SpawnCompanion(triss, 3, 1, 1, 1) ?Spawns 3 Triss'. All are invincible, have text above their head. The last one is displayed on the HUD.

RemoveAllCompanions()
Removes all companions from the world.

RemoveCompanion(optional count)
Removes up to 'count' companions from the world. Usually removed in the opposite order their were spawned in.

RemoveCompanionByName(name)
Removes a companion depending on what name was used to spawn them. This is case sensitive. So "SpawnCompanion(triss)" and then "RemoveCompanion(Triss)", will result in Triss not being removed.

SelectCompanion(optional number)
Selects either the closest companion to you, or the companion given by the number. So if you spawn Triss, then Ciri then Yennefer, calling SelectCompanion(3) will select Yennefer.
Selected companions have the text 'Selected' above their heads.

DeselectCompanion()
Deselects any currently selected companion.

CallCompanion(optional number)
Teleports the companion, given by the number, to your vicinity. If the number is not supplied, then the companion furthest away from you is teleported to you.

CallAllCompanions()
Teleports all companions to your location.

CompanionEquipTorch()
Makes the selected (or closest) companion you equip a torch in their hands.

CompanionLightTorch()
Makes the selected (or closest) companion light the torch in their hands, if there is one.

CompanionEquipShield()
Makes the selected (or closest) companion equip their shield.