Compiling:

You must have a copy of Visual Studio 2010 with SP1 installed.

Also required is the boost library, both includes and compiled libraries
If you don't have it, get boost from http://www.boost.org/
Compilation instructions (how to use bjam for your compiler) can be found at http://www.boost.org/doc/libs/1_51_0/more/getting_started/windows.html
Once compiled, make sure to add the include and lib folders to your VC++ directories inside Visual Studio.

The other 2 dependencies are project-local.
Because of their size, they aren't directly included into the project tree

Get poco from http://pocoproject.org/download/index.html (basic edition is sufficient)
It must be extracted into Dependencies10/poco folder, such that the folder structure matches the one in INSTRUCTIONS.TXT
After extracting, edit build_vs100.bat with a text editor, and replace the word "shared" in the last line with "all"
Optionally, you can also replace the word "samples" with "nosamples" for faster builds
After that, create a Visual Studio 2010 Command prompt, and invoke build_vs100.bat from it

Get tbb from http://threadingbuildingblocks.org/download.php
It is recommended to get the precompiled binaries for windows of the latest stable release
Compilation of this library will not be discussed here
Extract the downloaded archive into Dependencies10/tbb folder, such that the folder structure matches the one in INSTRUCTIONS.TXT

You are now ready to open Source/Hive.sln in Visual Studio 2010
From there, simply compile the Release configuration to get binaries that can be used in-game
The Debug configuration simply compiles an executable that runs some tests, and is not relevant here

Usage:

If you don't want to compile, you can download a prepackaged release for each revision from the github pages.
After successful compilation (or download of a prepackaged release), the Binaries folder should contain HiveExt.dll and Database.dll
Database.dll should be placed in the root directory of your game installation
If you don't have the TBB library installed to global system paths, those dlls should also be copied to the same dir as Database.dll
HiveExt.dll needs to go inside the currently used hive mod folder (usually @hive under the root dir)
While your customised copy of HiveExt.ini goes into your profile folder (server profile, like cfgdayz, next to the .RPT files)
For a description of available HiveExt.ini options, consult that file itself, where the descriptions are marked as comments

If you are going to run your own database server to connect to, look inside the SQL folder for the scripts that you need to execute on your database
the x_tables.sql files will create the tables, while the obj_sample_data.sql has the default spawn order for vehicles in it (make sure to change the instance id)
If you are already running some similar db layout, MAKE SURE to read the ENTIRETY of HiveExt.ini (especially the one about the Objects table name, and the PlayerID column)
to be certain that the parameters inside match what you are currently running as the database.

Final:

This project was started as a better alternative to the "official" Hive access library for DayZ,
however, since my request for making it the official Hive access dll was denied (at the time),
and that the most popular usage of it was running "private" or "local" servers for the game, 
I have removed all the restrictions and certificate systems that were in place, so that it can connect to any server you want.

Recently, after the founding of the DayZMod community that currently maintains DayZMod, this project DID become the official Hive access library.
Just compiling the source code isn't enough to connect to the public hive database though, for that, use the libraries distributed with the official server files themselves
Or, download a "blessed" version from the downloads page (blessed version is identical to the open source one, except that it can connect to the public hive by default)
You can (and it's preferred) to use the precompiled "blessed" version for connecting to your private hive as well, to save you from having to compile it yourself.

Hive access library by Rajko Stojadinovic (https://github.com/rajkosto)
If you would be so kind, and are satisfied with what this thing does, maybe send a donation my way to payment@rajko.info

Good luck with your DayZ hosting !