The alert reader will identify these codes as the codes from Unreal - 
no surprise since Klingon Honor Guard uses the same engine.

You must drop to console first by pressing the ~ key.

ALLAMMO - Gives you 999 ammo for all of your guns. 
FLY - Lets you fly around. 
GHOST - Lets you walk through walls. 
GOD - Makes you invulnerable to all attacks. 
INVISIBLE - Turns you invisible. 
KILLPAWNS - Kills all monsters. 
WALK - Turns off "GHOST" or "FLY". 
SLOMO # - Slows or speeds up the game. 1.0 is normal. 
SUMMON - Lets you add a weapon or an item to the world. (ie. SUMMON WEAPONNAME) 
PLAYERSONLY - Freezes time. Press again to resume time passage. 
OPEN MAPNAME - Jump to any map. (ie. OPEN MAPNAME) 
BEHINDVIEW 1 - Puts you in 3rd person style view. 
BEHINDVIEW 0 - Resets this.