The source code resides in the file OBG-BF.zip. Both hardware addition and the installation process are described in the ReadMe.txt file (in the archive too). The sounds are the same as in the original One Bit Groovebox device.
Meet PDQt, a Pure Data front-end built for Qt-based platforms. The mentioned platforms include Qtopia-based Sharp Zaurus (presently clamshell models only) and every platform supported by Qt3.
This is a first release, the program is still alpha, so do not expect too much. Still, the main functionality is already present, so — enjoy!