I have had the same problem. I have entered the exact labels in the code as shown in the manual (e.g. //*PURPOSE blah blah) but this is not placed in the documentation.
Has anyone used this feature? ...
The reason it does not work is that the driver assumes the data nibble is D5-7 and does operations (e.g. on tris) without refering to the structure you modified.
You will need to do more extinsive ch ...