I have one for my diamond drag...and I have no idea how it got there. I don't remember specifically downloading it. I called up the specialty bit in Aspire, built the file, and there it was in my post processor drop down list. I have no clue.
There was a post processor for the HUST controlled Elite series.
However, for the current RichAuto controlled Elite and Pro series machines...no drawknife custom post processors have ever been needed. Just leave the RPM set to zero.
...and...if you have the laser installed...you can flip the switch on the controller for the laser from "spindle" to "laser" and you won't have to worry about inadvertently activating the spindle from the machine controller.
I'm having trouble understanding how the drag knife works. I'm assuming the blade is directional and needs to be facing the correct direction in order to cut but how does the spindle orient it? My wife has a cricut and that is easy to understand as the tool only fits in one way and has a gear so the machine can rotate it as necessary.