Reporting variables back to a Java wrapper

I have a Kettle process and would like to set a variable within the process using something like Set Field Value or Set Variables.

I then plan on executing this Kettle transformation from within a Java wrapper. I can make the call fine, but cannot get the field or variable values out. In Java I can set variable names by calling setVariable on an instance of TransMeta. These variables can then be used by the Kettle transformation, but if I try getVariable on any variable set inside the Kettle transformation, I just get a response of null.

Is there any way to get a variable out of the Kettle transformation into the Java wrapper?