Using a Vanilla World, Creative Mode?

[feralswirl]

I copied a world that I wanted to use with Tekkit. The world was in Creative Mode. However, when I opened it through the Technic Launcher, it was in Survival Mode. I really need it in creative. Is there a way to turn it to creative now? Or what am I doing wrong, that it turns from creative to survival when I copied it - and how can I copy it and keep it creative?

[Valkon]

If you set NEI to cheat mode, you can change your game mode to creative from your inventory.

[feralswirl]

How do I do that?

[feralswirl]

Oh, found it. Thanks!!!