Some time ago I read an article written by a Russian programmer who took some interest in the game, disassembled and analysed the EXE, and found a lot of interesting stuff regarding the cheat codes and command line parameters. The original article is here but I'll summarise the key points.
The command line parameters are as follows:
/nocreatures - no monsters in levels (for multiplayer).
/nosound - disables sound effects regardless of the settings in the configuration file (CD music will still play if available).
/record - records a demo to the file DATA.VCR (I think giving another file name for the demo is also possible).
/playback - plays the demo recorded in DATA.VCR (perhaps other file names are possible too).
/null - connection method for multiplayer games.
/modem - connection method for multiplayer games.
/network - connection method for multiplayer games.
/h - launches the game in high-res mode (640x400) regardless of the settings in the configuration file.
/s# - the author doen't know what it does but # must be a number. Could be the skill level (as in other Build games), but Powerslave doesn't have any in-game difficulty level selection options.
/t# - once again the author hasn't figured out what it does, but launching the game without any number will give the player only one life at the start, and the status bar gets corrupted (comparison screenshot).
/cdoff - the game doesn't check if the CD is in the drive.
And here are the cheat codes:
KIMBERLY - displays the message "HI SWEETIE, I LOVE YOU", apparently addressed to the girlfriend of someone from the coding team.
LOBOLITE - activating this code should have displayed the message "FLASHES TOGGLED", however due to an error it gives the message "SNAKE CAM ENABLED" instead. The author of the article has tested if this code toggles lighting effects from weapons fire, as some sources indicate, or toggles lighting in dark areas of levels, as suggested by others, but apparently it does neither.
LOBOSNAKE - this is the code that should have had the "SNAKE CAM ENABLED" message. Activating it makes the camera switch to chase view of any cobra staff missile fired by the player.
LOBOSPHERE - reveals the entire map of the level. It was supposed to display the message "FULL MAP" when activated, but doesn't because of the same errors in the code.
LOBOCOP - gives all weapons and full ammo for each.
LOBODEITY - toggles player invincibility.
LOBOPICK - gives all keys.
LOBOSLIP - toggles no clipping mode.
LOBOSWAG - gives all items.
LOBOXY - toggles display of the player's current coordinates and FPS.
HOLLY - toggles debug console. The following commands can be entered:
GOTO x,y - teleports the player to [x,y] coordinates on the current level.
LEVEL ## - warp to level ##.
DOORS - opens all switch-operated doors and also activates all traps on the current level (the article's author speculates that this code simply activates all triggers in the level).
EXIT - finish current level.
CREATURE # - spawn a monster of type #. The types are:
0 - Anubis Zombie
1 - Giant Spider
2 - Mummy
3 - Piranha
4 - Bast Statue
5 - Magmantis
6 - Am-Nit
7 - Set
8 - Kilmaatikhan
9 - Selkis (?)*
10 - Kilmaat Sentry (?)
11 - Omen Wasp
* The article gives both 9 and 10 as "Alien Worker".
Well, the cheat codes per se are already listed in the tips/tricks area for the game, so this is more of a historical/research interest and curiosity (like the hidden message to a programmer's GF).