Had trouble enabling the console for Legends of Grimrock 1 on Mac OS X. This is how I got it working:

1. Find the config file on your system:

Mac OS X: ~/Library/Application Support/Almost Human/Legend of Grimrock/grimrock.cfg
Linux: $XDG_DATA_HOME/Almost Human/Legend of Grimrock/grimrock.cfg
Windows: %USERPROFILE%\Documents\Almost Human\Legend of Grimrock\grimrock.cfg

2. Find and edit the console and consoleKey lines (or add them if they don't exist). This example enables the console and sets F4 as the console key on OS X. Many other examples suggest using 192 (`) but that never worked on my Mac:

console = true
consoleKey = 115

3. See the LoG1 scripting reference for some available commands:
http://www.grimrock.net/modding_log1/scripting-reference/

Examples:

party:heal()
party:getChampion(1):levelUp()
for c = 1,4 do party:getChampion(c):levelUp() end