This presents a short tutorial on getting everything built and working on OSX. Keep in mind that if you're downloading the binary distribution [that .dmg thing with an application inside it], you shouldn't need to do this.

If you don't have OSX development tools [aka "XCode"] or don't know what they are, this isn't the post for you.

That being said, for people who like source, or developers, or whatever:

1) Download GPSD. You're looking for the .tar.gz file.

2) Extract and build it, installing it in your home dir [replace {version} with the one you downloaded]:
gzip -cd gpsd-{version}.tar.gz | tar -xvf-
cd gpsd-{version}
./configure --prefix=$HOME/gpsd/
make install
3) You need the serial device entry to connect to your gps receiver. On OSX, it's likely to be /dev/cu.{something}, especially for bluetooth devices.

4) In a terminal, run:
cd ~/gpsd/sbin
./gpsd -b -N /dev/{your-gps-device}
If you see screenfulls of stuff scrolling by, it probably means gpsd is working.

5) Read this warning. Having fully comprehended it, at your discretion you may try removing the "-b" option from gpsd above, which can improve the general behaviour and performance of gpsd.

6) The "GPSD Launch Wizard" in the UI neatly maps onto everything you've just learned [including "safe mode" mapping to -b]

Keep in mind that if you download the binary OSX version from the obd gps logger website, you can completely skip all this, except for the "work out what your serial device yours is" step.

Have fun,
Gary (-;