The DITA For Publishers materials are provided as a single Zip package from the project's download page: https://sourceforge.net/projects/dita4publishers/files/. The Toolkit plugins are intended for use with the 1.5, 1.6, and 1.7 versions of the Open Toolkit but may work with the 1.4.3 version. The DITA for Publishers plugins are tested against the latest stable and milestone releases. Note that release 1.5.4 fixes a number of bugs from 1.5.3. The 1.5.4 release has proven stable for me and I recommend moving to that release if at all possible. Note that for 1.7 there are a few minor code differences from 1.6 that require a separate build of the D4P plugins, identified by "OT17" in the materials package filename.
There are many ways to do this, but one way is to use a command window. Navigate to your Open Toolkit's directory and then issue this command:
tools/ant/bin/ant -f integrator.xml
That should run and you should see some sort of happy message.
c:\Program Files\oxygen\frameworks\dita\DITA-OT > ..\..\..\tools\ant\bin\ant -f integrator.xml
c:\DITA-OT > startCmd.bat
The, using the command window you just created, this command should work:
java -jar lib/dost.jar /i:/Users/myname/dita4publishers/sample_data/wizard-of-oz/wizard-of-oz.ditamap /transtype:epub
Specifying the actual path to where you put the sample data.
java -jar lib/dost.jar /i:\Users\myname\dita4publishers\sample_data\wizard-of-oz\wizard-of-oz.ditamap /transtype:epub