Not sure if you sorted this out already, maybe the forum "Post Processors for MC" would be more appropriate...
I hacked into my post and edited to what I needed. The path and file name to my 4th axis post is...
C:\Users\Public\Documents\shared mcamx5\MILL\Posts\Generic Fanuc 4X Mill.pst
You should start by creating a sub-folder like C:\Users\Public\Documents\shared mcamx5\MILL\Posts\Generic\default and back up the post there in case you really screw up and have to start over.
I would then open up the post with the MasterCam editor as it make it much easier to read.
Before making a change to a line save it in a comment and also tag it somehow so you know it was your change, for instance I changed the line...
fmt "XY STOCK TO LEAVE - " 2 xy_stock #Note format
to two lines, the 1st with the orignal code which I added 'tony original-> and the 2nd line that I edited.
#tony original->fmt "XY STOCK TO LEAVE - " 2 xy_stock #Note format
fmt "XY " 2 xy_stock #Note format
I haven't hacked into my 4th axis but if I had your issue I would 1st try changing the aaxisx variable from 1 to 0.028
so from
aaxisx : 1 #A axis rotation vector constant
to
aaxisx : 0.028 #A axis rotation vector constant
Definitely be careful...