The guide also works for DARKCORP v1.1.
No, you don't understand this.
Installing DARKCORP v1.1 after updating this IOS isn't going to get you anywhere: the DARKCORP installation WILL overwrite the updated IOS, which will leave you with the same IOSes as you have now.
Use NeoGamma to play this game, and keep DARKCORP for other games (not recommended), or use NeoGamma for all your games, and delete DARKCORP (recommended).
You can also use USB loading, but that is a whole other story...