I don't use KOReader, sorry.
As for the builtin reader, I have tested it and sure enough you can use "reader" instead of "kindlet" and it will open a document in the builtin reader.
Works:
Code:
lipc-set-prop com.lab126.appmgrd start app://com.lab126.booklet.reader/mnt/us/documents/Warbreaker_B002KYHZHA.azw3
But what I have not been able to figure out is, how to inform lipc about a filepath containing spaces. I have tried standard shell escaping, and using quotes. Both return the standard "the application could not be started" message.