Custom script printing - is it actually possible?

[SrgBrisbane]

Hello there.
Well... I cant find anything enywhere about my issue, so Im feeling quite odd, like Im missing something...
As far as I know thee should be a way to use custom script for pickslip print, but I cant find any tips how it can be done. Cant see any option at BrickStore itself and cant find any proper files in folder.
Any hints where I can place script file, change "Classic Layout" to new one and use it actually?
At BrickStock it was quite easy. Folder "print-templates" was just there... copy -> change name -> modify -> done

Thanks!