Easiest? Contact the folks that are administering the Wireshark download kit for OS X, and tell them that it's broken, and pass along the errors you're getting.
The Wireshark installer package deals with the installation itself; with locating the tools in the expected places. (Wireshark is clearly not set up as a Mac application bundle - which you could then drag where you want - and these bundles can also incorporate prerequisite parts such as Freetype directly into bundle.)
As for your core question, what is involved here is troubleshooting and porting the code. Fixing the problem that Wireshark installation is having. If you're interested in that process, then what you're doing is setting up the proper prerequisites.
This means getting the proper version of Freetype configured, and in the right spot. And whatever else might then be needed.
This is also why I mention backups, too. These installation processes can sometimes hose parts of your OS X installation, should something go wrong. (And it's been my experience that this stuff usually works, but - things do occasionally get twisted together and go wrong.)
Those backups are your path back, if (when?) there's a problem or a conflict, if you decide to follow through here. You're going to be operating in the command-line environment to get this to work; directly with Unix, the gcc or llvm tools, and with bash.
There are various ways that software can get onto your boot disk.
- It can be due to an operational failure or a software vulnerability (such as Flashback, or downloading a software kit from an untrusted source, or downloading what should be trusted software from a security-breached source) - you generally don't want these packages installed on your system.
- It can be an application bundle. These are the applcations that you drag to your Applications folder, or to your local Applications folder if you've created that, to install them.n These application bundles can and often do contain most or all of the prerequisite packages within within the bundle. Getting rid of these means dragging the bundle to the trash. These are the easiest to deal with.
- There are installers, which is what Wireshark is currently using. These packages are downloaded, then you execute the installer to move the software into the location the package developer has decided. That's usually into the Applications folder, though it can (and probably also does) also move other software pieces into other directories. Deleting these can involve running a tool to remove the various parts that were installed.
- There are packages that are installed and moved locally. If you're going to get the proper version of Freetype loaded, this is what you'll be dealing with. There are packages which can potentially help here (and sometimes not) called MacPorts or Fink; these can manage prerequisite packages. Off the top, I don't recall if Freetype had any prerequisites. I don't think it does, but haven't confirmed that.)
As for porting Freetype over, Google around for details on how that usually works. Or see if the Wireshark folks know that their installer isn't working in your particular configuration, and if they can get a fix available.