CartridgeBuilder is designed to take a configuration file and output a CRT image file. There are a lot of configuration options which are best demonstrated by the included examples.
The Legacy of the Ancients + Legend of Blacksilver combo cartridge was created using CartridgeBuilder, and you can see the final product here: http://csdb.dk/release/?id=128480
CartridgeBuilder is a command-line application built in C#.
More documentation to come later.