@geekmaster: I'm pretty sure (cf. the OP) the JB still works (granted, the two reboots method, but still).
The problem is mostly that the doc/files are completely wrong/outdated on the WiKi for FW 4.1.0 right now
The second problem is that none of us *have* a K4B, and very few of us had a K4S, simply because it's not a very interesting device for our purposes (and we don't have unlimited funds to throw at Amazon for fun ^^). And since most of us prefer to actually write doc for stuff we're sure about/can test/debug, the K4 wiki never took off, and is now in a pretty sorry state.