Perhaps it may seem more complicated than it is.
Download blorbtool.py from here: https://github.com/erkyrath/glk-dev and place it in the game directory.
After compiling, you navigate to the game directory in Terminal and type (or paste) that line, with GAME replaced by the name of the game. If the name contains spaces, you will need to insert quotation marks.
Example for Counterfeit Monkey:
python blorbtool.py "Counterfeit Monkey.materials/Release/Counterfeit Monkey.gblorb" giload "Counterfeit Monkey.materials/Release/interpreter" interpreter