Chroma,
I am a little unclear about your question. You should be able to use BuildTargetBuildSpecification to build all or selected build specifications within a project. You could build a program to call this VI for different projects and build specifications.
Are you looking to find out all builds present in a project, similar to how the other example you pointed too adds files? If so, have a look at the attached screen shot. This opens the project, gets all descendents of type "EXE" (application builds), and creates an array of their names. If you don't specify "EXE", it will return all project descendents (builds, VIs, libraries, etc...). The help for the "Get All Descendents" method lists other possible types that you can specify besides "EXE" that might be useful, such as "VI", "DLL", "Source Distribution" and "Installer".
I hope that helps!