http://docs.kde.org/stable/en/kdemul...ng_howtos.html
... which you've seen.
1. make sure Kmix has the mic enabled
(1a. make sure the mic is in the correct jack - the label on the jack means just that: jack - you'll probably have to fool around a bit.)
2. run arts in full duplex
(press Alt+F2 and enter kcmshell arts: On the second tab-page you have to make sure the checkbox for full-duplex is selected, clicking Apply restarts aRts which means that you have to restart KRec too.)
3. check VU meter flickers when you blow on the mic
(this is where you can try different jacks, in case the mic jack ain't.)
Then you can record like you would for an internal stream.
What you seem to need is some way to tell if it is your hardware or your software configuration wot is letting you down. Have you tried recording from an internal stream first? If this works, then it is the mic side of things that is the issue.
