Every now and then, I'll see a dev suggest changing something in build.prop or another file in their ROM. I've always been a bit skittish about that, mostly because I've never seen how one does it. Is it as simple as finding a file in the ROM's .zip archive, editing it, then repackaging the whole thing? What do I need to know about signatures? Tips, hints, instructions: give me any info that's helpful and handy!