EVEMon is written in mostly C#, targeting the .NET Framework 2.0, with a very small amount of unmanaged C++. The installer is built using NSIS, and the project file is best opened with Visual Studio 2005.

If you have Visual C# Express (available for free from Microsoft), you will be able to work with the bulk of EVEMon.

Source code can be checked out using a Subversion client of your choice (I recommend TortoiseSVN). The repository URLs are as follows:

Latest Development Source Code: svn://svn.battleclinic.com/EVEMon/EVEMon/trunk
Version Release Source: svn://svn.battleclinic.com/EVEMon/EVEMon/tags//

If you do not have an SVN client and would like to view the EVEMon source code in your web browser, you can do so here.

Patches can be submitted via the trac system. A diff generated against the trunk using TortoiseSVN is the preferred format, especially for large patches. Commit access to the repository will be given to contributors who've shown a history of submitting good patches.