Since these utilities are mostly fairly straight-forward, it isn't strictly true to call these frequently asked questions, because I've only been asked them once or twice. Nevertheless, they could prove useful!
Steps 1-4 are the setup - which means you only have to do them once - then steps 5-8 are the basic steps of how to run gps2geX.
The current version of gps2geX requires you to have gpsdX or another installation of GPSd set up on the computer where you're running it, even if you aren't connecting to the local machine for gpsd. If you haven't installed gpsdX on your computer, do so!
I know there are a few people interested in running gps2geX but never connecting the GPS unit to the machine running gps2geX... and I'm working on a version which will run without GPSd installed.
Although the GPS unit itself probably doesn't need a driver, it almost certainly incorporates a chip inside it called a PL2303, made by a company called Prolific... and that chip needs a driver for your computer to find it.
You can download the driver from the Prolific web site. Once you have installed the driver and rebooted, plug in your GPS and run gpsdXConfig again - you should see something like /dev/tty.usbserial appear in the list now: that is your GPS, so Select & start.
"But the unit has a USB connector already", I hear you cry. Unfortunately Garmin, in their infinite wisdom, decided to use a proprietary USB connector in this series of units, and they don't offer a driver for the Mac for that connector (Garmin's Mac support has historically been very limited, but this may change soon). On the bright side, their serial connector on the same unit is much more standard, so you should be able to get it to work with a Keyspan USB-to-Serial adapter and the Garmin serial connector cable. Alternatively, you could just buy a cheap USB GPS "mouse" such as a Holux GM-210 or a GlobalSat BU-303, probably for less than the cost of the Keyspan adapter and the Garmin serial connector.
N.B. This answer is quite new, and I have not yet heard from anyone who has implemented this solution (either successfully or otherwise). However, information on another Mac GPS program's FAQ suggests that this should work with gpsdX.
This is something which many people ask for, and which is somewhere between really difficult and impossible to execute. However, it's the wrong question (yes - I asked it too). The right question is "How hard is it to add GPSd support to an existing program?" The answer to that question is "incredibly easy".
So, what can you do? E-mail the developers of the program you want to support GPSd! GPSd is open source, and provides a simple API for accessing GPS position information from any GPSd server. It takes about 10 lines of code to add a basic GPSd connection to an existing GPS program, and perhaps another 20 to take full advantage of the API... but wait, there's more: when you contact the developers of those programs, tell them that I am prepared to offer FREE development assistance to any developer of an existing GPS program for Mac that wants to support GPSd.