Short explanation video: https://youtu.be/deN8cRzTUzk
Some ideas picked up from:
http://www.logicprohelp.com/forum/viewtopic.php?f=45&t=117980
And logic setup needs to be tweaked:
Preferences>Audio>General>Sample Accurate Automation "Volume, Pan, Sends & Plug-In Parameters"
must be selected for proper timing
Keyswitches in Shreddage must be setup to be identical to the script (or vice versa).