As the linked post mentions, Legend of Grimrock stores everything user related in osX's Application Support folder, not your Documents folder.
Its worth noting that in the latest version of osX (Mountain Lion 10.8.X ) and possibly in Lion (10.7.x) too the Library folder where the Application Support folder is located, is hidden. You can't see or find it by casually browsing within Finder.
When using the latest versions of osX, to get to the folder you need to put your custom portraits and/or find your saved games you need to use Go to Folder...
within the Go
menu in Finder (shortcut: Command+Shift+G). Then type in:
And press Return/Enter
It will open up your user Library folder and let you browse to Application Support/Almost Human/Legend of Grimrock/
folder, where your saves and the Portraits folder are located. This folder is auto generated per user after they run the game once. So if you're playing the game that was installed by another user on the same machine you must run it once before trying to add new portraits or transfer save games.
Excellent. It worked! Thank you very much!