Well I decided to make a mini tut' about this, incase nobody knew how to pull this off.
Part1
Using Corsix's sga reader, extract "tuning.lua" from Gamedefault (lies in campaign folder) sga open this file out in wordpad, or notepad++
search for this:
Code:
-- this references Config/defaultChapterColours.lua player_chapter_names = { "SM_Bloodravens", -- player 1 "SM_Bloodravens_COOP", -- player 2 (co-op) },
Part2
Once you have gotten the file extracted, you could edit the SM_Bloodravens part of the file with your own like for example:
SM_Darkangels
SM_Whitescars
And so on, also you could edit the coop file too, so whoever your playing with would show up with that designated colourscheme (only playable online with somebody who has the mod I would assume.)
And you can also put in you custom schemes, just type
"colourschemenamehere" and it should work (Haven't exactly tested that yet, but will do.)
And refer to Copernicus's Sga packing tutorial here
http://forums.relicnews.com/showthread.php?t=215592 if you need help with sga packing or use the -dev parameter.
there you have it, hopefully this tutorial helped you =D.
And as you can see I have sucsessfully changed Blood Ravens to Novamarines:
Oh and if you want the colour schemes to appear every where, edit the defualt chapter colours lua.
Getting your colours into the Blood Ravens colourscheme.
Ok, first things first, open up gamedefault.sga with Corsix's sga reader, and go to config, look at the right hand side there should be alot of .lua's extract "defualtchaptercolours.lua" open it up once you have extracted it, at first you should see this:
Code:
{ { chapterKeyName = "SM_Bloodravens", chapterNameID = 9109487, -- LOCDB [9109487] 'Blood Ravens'--~ chapterNameID = 9109488, -- LOCDB [9109488] 'Blood Ravens Chapter' primaryColourName = "Blood Raven Red", secondaryColourName = "Bone", tintColourName = "Chaos Black", extraColourName = "Metallic Gold", teamTex = "1", badge1Tex = "sm_Bloodravens", usableRaces = { "race_marine" }, armyPainterVisibility = true, },
This is the file you want editing, if you want info on the colours extract armypaintercolours.lua in config also.
And there you have it, you very own custom made campaign colour scheme!
Use wordpad not notepad when editing the luas.
The game loads the first one found (alphabetically) so I just insert one before DOW2.module. I also build a custom module based on which modules are selected, which allows people to combine any number of mods, rather than just load the one. 
