Inevitable Disclaimer: by installing this software you implicitly absolve the author of any responsibilities relating to it's use and accept that it may potentially (as for all software) cause damage to your hardware and/or other installed software.
Because Apt is such a flexible tool, some of the combinations offered will not work as expected.
Download the full version and its source code at: http://www.eskimo.com/~jibanes/
If you want to play with the source code and build your own version of Apt, follow these instructions.
Note that the DB files created by the various versions are not always compatible: when testing a version, it's best to save your Apt-DB.pdb file and then delete it to make a clean start.