Speaking of the PDK, installing it in your OC4J (Oracle Container for Java) is unfortunately not a trivial or drag-and-drop type operation. Luckily Oracle provides a detailed document explaining the installation steps (http://www.oracle.com/technology/products/ias/portal/html/installing.pdkjava.v2.html).
Surprisingly, I've never actually had any problems installing the PDK when following these directions. Pretty unusual, often Oracle's directions leave something to be desired.
But of course I've never had to install it on a standalone OC4J. Only in an OC4J created by the Portal OEM (Oracle Enterprise Manager). I assume it should be just as simple in the standalone case but I can't promise that.