Hi,
I have followed your instructions and any other I was able to find, but I still didn't solve my problem.
I got the latest ALSA-Configuration.txt, installed kernel-source.rpm, updated and installled: alsa, alsa-driver-kmp-default, alsa-utils, alsa-tools, and alsa-firmware.

With head -n 1 /proc/asound/card0/codec* I get:
==> /proc/asound/card0/codec#0 <==
Codec: Motorola Si3054

==> /proc/asound/card0/codec#1 <==
Codec: Realtek ALC883

Which is a bit strange, since Motorola is my modem. Still I hoped that it will use ALC883. I searched for it in ALSA-Configuration.txt and tried every option that is under ALC883/888. I edited the sound in modprobe.d to use every one of these, but I still have output on both laptop speakers and headphones. After every change, I have restarted sound system and started kmix.
Does anyone have the solution for this one? Two days I'm trying to figure this one out, but without success.

ALC883/888
3stack-dig 3-jack with SPDIF I/O
6stack-dig 6-jack digital with SPDIF I/O
3stack-6ch 3-jack 6-channel
3stack-6ch-dig 3-jack 6-channel with SPDIF I/O
6stack-dig-demo 6-jack digital for Intel demo board
acer Acer laptops (Travelmate 3012WTMi, Aspire 5600, etc)
acer-aspire Acer Aspire 9810
medion Medion Laptops
medion-md2 Medion MD2
targa-dig Targa/MSI
targa-2ch-dig Targs/MSI with 2-channel
laptop-eapd 3-jack with SPDIF I/O and EAPD (Clevo M540JE, M550JE)
lenovo-101e Lenovo 101E
lenovo-nb0763 Lenovo NB0763
lenovo-ms7195-dig Lenovo MS7195
haier-w66 Haier W66
6stack-hp HP machines with 6stack (Nettle boards)
3stack-hp HP machines with 3stack (Lucknow, Samba boards)
auto auto-config reading BIOS (default)