Quick question - I'm attempting to alter shadow flash (fully aware of the risks; I've successfully done it already and am experimenting with the process). Is it possible to edit the shadow block directly during the process of programming the chip (i.e. have a defined data section that gets loaded directly to Shadow Block A alongside the rest of the main program), or can it only be modified by a function executing from RAM?
Yes, it is possible, if particular programmer have defined programming algorithm for shadow flash (for instance PeMicro debugger have them prepared …\pemicro\algorithms\shadow\).
Production programmers should be capable to do it as well as it can be just a requirement to set up censorship during production programming.