The build process uses several marvin plugins. Most of them are available via the usual plugin repositories.
Last time i tried, i had to build two plugins myself: cpptasks-parallel and maven-nar-plugin
mkdir workingdir
cd workingdir
git clone http://github.com/duns/cpptasks-parallel.git
cd cpptasks-parallel
mvn install
cd ..
git clone http://github.com/duns/maven-nar-plugin.git
cd maven-nar-plugin
mvn install
cd ..
To fetch this javax.usb implementation create a directory where it should reside, cd into it and clone it:
git clone http://github.com/trygvis/javax-usb-libusb1.git
Inside the repo is a referenced external repo, which houses Trygve's branch of libusb. To fetch, build and install it (notice that you have to provide an absolute path to libusb.home):
git submodule init
git submodule update
cd libusb
mvn install -Dlibusb.home='absolute-workingdir/javax-usb-libusb1/libusb-git'
After that a simple mvn install in the root directory should work.