Yes , it's true .
The SKEDARS have invaded the Combat Simulator in Perfect Dark.
You have to defeat them.
They are even showing there real faces in the Solo Missions.(new scenario's)
You can find the gameshark codes and the action replay codes on this link.

http://home.wanadoo.nl/hack-master-64

hackmaster did it again.

I've a lot more codes for a lot of N64 games