- Navigate to your ME2 CookedPCConsole folder
- For me the location is: D:\Program Files (x86)\Steam\steamapps\common\Mass Effect Legendary Edition\Game\ME2\BioGame\CookedPCConsole
- Backup your original Coalesced_INT.bin file and then replace it with the modded one.
- In game you should now find Morinth's armor in your casual appearances and armor. You can make it visible by changing all the 
  armor slots to empty except for one. Otherwise the armor won't show in missions. I usually leave a visor on or maybe a shoulder piece.
- Bonus: Want Miranda's breather mask? Put numlock on and press 4 on your numpad on the Normandy. You should now have Miranda's breather mask
  available in the helmets section. 
  Tho you can't count that as one a "visible" piece of armor unfortunately. So you'll probably still need to have a visible shoulder pad etc.