Back up your EXE, load up a hex editor, and make the following changes to enable these modes.

Debug Mode
0x1012A6 - 00 -> 01

Notes:
Should be equivalent to adding SetPrivateProfileString('Program Options','Debug Mode','1') to baldur.lua
Better reference than below - https://gibberlings3.github.io/iesdp/appendices/clua/bgee.htm
Ctrl-2 - Fade screen out
Ctrl-3 - Fade screen in
Ctrl-4 - Box interactive objects
Ctrl-J - teleport to cursor
Ctrl-N - Unknown, flashes screen red
Ctrl-X - Popup more detailed mouse position info
Ctrl-Space - Bring up console. Click "Show" for cheat menu.

Theoretical Console commands - Precede with C:. Eg: C:DisplayText("test")

DisplayText
MoveToArea
SetCurrentXP
CreateEngine
StartStore
CreateCreature
CreateItem
ExploreArea
SetWeather
PlaySound
AddGold
EnableCheatKeys
AddSpell
AdvanceRealTime
DisplayAllBAMFiles
TestAllDialog
PlayMovie
ResetAchievements

...There are a bunch more, I'm not dumping them all here. ...Yet.

Developer Mode
0x1012BD - 00 -> 01

Notes:
I can't seem to find anything that this enables.

UI Edit Mode
0x1012F7 - 00 -> 01

Notes:
F11 - UI Info

No Movies
0x101308 - 00 -> 01

Any insight on the debug/dev features would be appreciated.

No need to hex edit the .exe file. Just open your Baldur.lua file (found in "My Documents\Planescape Torment - Enhanced Edition") with any text editor and add SetPrivateProfileString('Program Options','Debug Mode','1') to the end of the file.

Here's a list of the item codes you can use with CreateItem:
http://bootstrike.com/Torment/Online/tnfo5.php

Here's a list of spells. These should also be added using CreateItem (to get the spell scroll):
http://bootstrike.com/Torment/Online/tnfo3.php

Examples: Press CTRL+SPACE to open the cheat console, then type...
C:CreateItem ("golring") -- adds a gold ring to your inventory.
C:CreateItem ("SPWI101") -- adds a scroll for Chromatic Orb to your inventory.

Note that capitalization matters: be sure to type CreateItem and not createitem.