There is no documentation yet, but hopefully the user interface makes it fairly easy to work out.
One point: the QPAC picks a file off the file system, NOT out of a process variable. The file must be accessible from the Workflow server machine, not the user's machine.
Please let us know if you encounter any problems, or if you need any enhancements.
Also, please note that in order for this QPAC to work, it has to introduce a "dummy" task into the task history within Form Manager. We're hoping to come up with a more elegant way of solving this at some point, but this will require a lot more code, and I wanted to give you something that works. Hopefully this is just a minor inconvenience.