You must enter the cheatsat the console. To get the console, right-click on sof.exe in your directory and choose "Create shortcut" and then right-click on the shortcut you've created and choose "Properties". Change the command line to add this:
+set console 1

It should look something like this when finished:
"c:\....\SOF\sof.exe" +set console 1

In the game, bring up the console by pressing "~"

Code	Result
heretic	God Mode
phantom	Walk Through Walls
ninja	Enemies Don't See You
defaultweapons	Give Default Weapons
elbow	Give Weapons 1-5
bigelbow	Give Weapons 6-10
matrix #	Timescale (replace # with 1-10)
gimme X	Spawn Object/Item X
updateinvfinal	Gives More Ammo
killallmonsters	Kills All Enemies
map X	Goto Level X (See Below)
kill	Unknown
putaway	Unknown
destroyents	Unknown

Level Names
(use with map X cheat):

tut1, tsr1, tsr2, trn1, arm1, arm2, arm3, kos1, kos2, kos3, sib1, sib2, sib3, irq1a, irq1b, irq2a, irq2b, irq3a, irq3b, ger1, ger2, ger3, ger4, nyc1, nyc2, nyc3, sud1, sud2, sud3, jpn1, jpn2, jpn3

Spawning Objects
To spawn objects, follow these commands to list all possible items to spawn, then to actually create the item:

1) Type: DEVELOPER 1 in console first. (this allows you to list the entities).
2) Type: ENTLIST, this will list the entities, and most things in the list are spawnable.
3) Use the GIMME cheat command to spawn the item.

Example: gimme item_weapon_microwavepulse will spawn the Microwave Pulse Gun.

Items Listing

Weapons
GIMME item_weapon_pistol = 9mm
GIMME item_weapon_pistol2 = .44
GIMME item_weapon_shotgun = Shotgun
GIMME item_weapon_sniper_rifle = Sniper Rifle
GIMME item_weapon_machinepistol = Silenced 9mm
GIMME item_weapon_assault_rifle = SMG
GIMME item_weapon_machinegun = MachineGun
GIMME item_weapon_autoshotgun = Slugthrower
GIMME item_weapon_rocketlauncher = Rocket Launcher
GIMME item_weapon_flamethrower = Flamethrower
GIMME item_weapon_microwavepulse = MicrowavePulseGun

Ammo
GIMME item_ammo_sp_pistol (9mm)
GIMME item_ammo_sp_pistol2 (.44)
GIMME item_ammo_sp_shotgun (shells)
GIMME item_ammo_sp_slug (slugs)
GIMME item_ammo_sp_rocket (rockets)
GIMME item_ammo_sp_gas (flamer)
GIMME item_ammo_sp_battery (MPG)

Items
GIMME item_equip_armor = Body Armor
GIMME item_equip_medkit = MedKit
GIMME item_equip_c4 = C4 Explosive
GIMME item_equip_flashpack = Flashbang's
GIMME item_equip_grenade = Hand Grenades
GIMME item_equip_light_goggles = nightvision
GIMME item_equip_claymore = Claymore Mines