Solved, finally ) I got my ALC888 working on ICH7 (MSI-7236 aka MSI 945 Neo5-F based on i945GC + ICH7) using modified AppleAzaliaAudio.kext

Pros:
+ Native Apple kext without any injectors or enablers.
+ Nice, stable and clear sound without any cracks or noise (especially comparing to VodooHDA)
+ Easy configuration and installaion (comparing to AppleHDA modding).
Cons:
- AppleAzaliaAudio.kext is an obsolete 32-bit driver, so you'll have to enable 32-bit (i386) kernel mode in Chameleon bootloader (actually, i haven't noticed any difference between LP86_64 (64-bit) and i386(32-bit) kernel modes - both work fine on my PC without any impact on RAM amount available or application performace).
- AppleAzaliaAudio.kext supports stereo output only, inputs not working at all (this is not a problem for me, because I've got a high-quality mic integrated in my USB-webcam, and it works fine).
- You'll need Windows + Realtek drivers installed for initial config (to get your audio device hardware IDs).
So, I suppose you've got Windows (XP, Vista, 7) installed with HDA audio drivers properly configured (sound working).
1. Login to Windows, right-click Computer (My Computer) and click "Manage".
2. On the left side, find Device Manager and click it.
3. On the right side, you'll see a list of your devices. We need two main audio devices -
Realtek High Definition Auio (under Sound group) and
Microsoft UAA Bus Driver for HDA (under System Devices group).
4. Double-click each of this devices, open Details tab and choose Hardware IDs in the drop-down list. Save to text file or write down these IDs. You'll get something like this:
Realtek High Definition Auio
------------------------------------------
HDAUDIO\FUNC_01&VEN_
10EC&DEV_
0888&SUBSYS_103C2A8C&REV_1001
HDAUDIO\FUNC_01&VEN_
10EC&DEV_
0888&SUBSYS_103C2A8C
Microsoft UAA Bus Driver for HDA
------------------------------------------
PCI\VEN_
8086&DEV_
27D8&SUBSYS_2A8C103C&REV_01
PCI\VEN_
8086&DEV_
27D8&SUBSYS_2A8C103C
PCI\VEN_
8086&DEV_
27D8&CC_040300
PCI\VEN_
8086&DEV_
27D8&CC_0403
5. Now we combine the bold figures above and get the following strings for each device:
Realtek High Definition Auio 0x10EC0888
Microsoft UAA Bus Driver for HDA 0x27D88086
6. Login to Mac OS X and download any AppleAzaliaAudio.kext you like from the internet - I just downloaded the original Apple kext version 1.0.0.0.
7. Right-click your downloaded AppleAzaliaAudio.kext and choose Show Contents. Open AppleAzaliaAudio.kext/Contents/Info.plist and find &--#60;key&--#62;IOHDAudioCodecVendorID&--#60;/key&--#62;. Add your codec string 0x10ec0888, then Save and Close the file.
8. Open AppleAzaliaAudio.kext/Contents/PlugIns/AppleAzaliaController.kext/Contents/Info.plist and find &--#60;key&--#62;IOPCIPrimaryMatch&--#60;/key&--#62;. Add your HDA bus string 0x27D88086, then Save and Close the file.
9. Remove all kexts with *HDA* in filename from Extra/Extensions and System/Library/Extensions (i suggest moving rather than deleting files).
10. Copy your modified AppleAzaliaAudio.kext to System/Library/Extensions.
11. Run Kext Utility to rebuild cache and repair permissions.
12. Launch Chameleon Wizard and tick "32-bit mode" for kernel (arch = i386).
13. Reboot
Sound working now!!!
Update: Now, when I've gained some Mac OS X configuration experience, I'm looking forward to making a more complicated solution using AppleHDA.