Sorry i guess i should elaborate since there are 4 versions of the minipac + harness.
It's the $50 model: Mini-PAC standard, with 28 switch harness plus ground harness and USB cable.
It comes with the harness that looks like an IDE connector. If I'm not mistaken the harness for the trackball / spinner plugs in to the smaller header(does not come with). I could be wrong as I havent used one yet and the unit is still in the sealed package. Here's a pic of what I think is correct for the trackball spinner.