The source code for a former version of the ABC4Trust Engine (as announced in the ABC4Trust press release of December 2013 by the ABC4Trust consortium) can be downloaded here. Please note that this version is outdated.
Also see the ABC4Trust hotel room booking scenario: The scenario showcases most of the features provided by reference implementation, namely issuance with carry-over, verification and revocation of credentials.
The demonstration is deployed within a virtual machine.You can follow all steps from obtaining a credential, to make use of it and revoke it in the end. (Download Virtual Machine) For further details please read D4.2 - Final Reference Implementation.