If you want to play this mod in Dark Crusade instead of Soulstorm, you must edit the Racetables.scar file. It is located in the CampaignMissions/data/Scar folder, and can be opened in Notepad or any other text editor.
Find the following entries:
space_marine_squad_tempest
ork_squad_fighta_bomba
eldar_squad_nightwing
eldar_aspect_stone_nightwing
eldar_research_nightwing_regen
chaos_squad_hell_talon
guard_squad_marauder
addon_guard_marauder_depot
guard_research_convoy_armor
guard_research_convoy_armor_2
Delete those lines (the entire line; not just the names listed) and save.
Put the mod in your Dark Crusade folder and play.
Thanks to TheSaltyBrit for testing.
Update for version 3:
Open DXP2Dummy.module and delete the following lines:
ArchiveFile.3 = DXP2Data-New
ArchiveFile.9 = DXP2Data-Whm-%MODEL-LEVEL%-New
Adjust the numbers on the remaining archive files so that it's 1-8.
The deep strike buildings for imperial guard and orks don't work in Dark Crusade, so go to Data/attrib/ebps/races and delete the guard and orks folders.
Open Data/scar/scarutil.scar. Find guard_deep_strike_building and ork_deep_strike_building (2 instances of each) and replace all of them with chaos_single_player_only_sacrificial_circle. This will cause their commanders to teleport in instead of using their transports, but it is only a visual change, and the rest should work fine.
There's one more file that has been causing me Fatal SCAR Errors. Remove the line for the research for Eldar Nightwing Regen. It will allow the missions with eldar to load