Thanks flip360 for your input.

I have managed to get the ML installed, but I had to take some kexts from the working 10.6.8 and put in the /Extra folder as a dropping replacement for making the Installation process complete. I was also able to boot the installed ML, but several things were not working.

Here is what I did:
- Used Chameleon 2.1 r2042; without this, I was getting a constant reboot right after loading all the kexsts on the USB key
- Used original kexts from 10.6.8 for: AppleAHCIPort.kext, IOAHCIFamily.kext, IOUSBFamily.kext, IOUSBMassStorageClass.kext and put then in /Extra (not /S/L/E). It is important not to replace the original files, because the installer does some kind of authentication test, and fails the Installation if you replace the original files. Having them in /Extra/KextStore serves the purpose of overriding the original ML kexsts correctly.
- Generated a very generic EFI string for the graphics, because after doing the steps above, I could see through the USB LED activity that the Installer were properly loaded, but I had Black Screen. So, I used OSX86 Tools to generate a GFX EFI string and put it in org.chameleon.Boot.plist as below. It really was just no paying attention to the real values or anything, just a generic one but enough to get a graphic back. Not QI/QE though, very choppy and slow graphic... hope we find a solution to this soon:
<key>device-properties</key>
<string>6802000001000000010000005c0200000d00000002 010c00d041030a000000000101060000100101060000007fff 04001e00000072006f006d002d007200650076006900730069 006f006e0000002c0000006e5669646961204765466f726365 20473130324d204f70656e474c20456e67696e65205b454649 5d22000000400030002c006400650076006900630065005f00 740079007000650000000b000000646973706c617910000000 4e005600430041005000000018000000040000000000010006 00000000000000000000000e0000006e0061006d0065000000 0b000000646973706c617914000000400030002c006e006100 6d0065000000120000004e5644412c446973706c61792d4110 0000006d006f00640065006c000000180000006e5669646961 204765466f72636520473130324d0e0000004e00560050004d 00000020000000010000000000000000000000000000000000 0000000000000000000014000000400031002c006e0061006d 0065000000120000004e5644412c446973706c61792d422000 0000400031002c0063006f006d00700061007400690062006c 00650000000e0000004e5644412c4e564d6163220000005600 520041004d002c0074006f00740061006c00730069007a0065 000000080000000000002020000000400030002c0063006f00 6d00700061007400690062006c00650000000e0000004e5644 412c4e564d616322000000400031002c006400650076006900 630065005f00740079007000650000000b000000646973706c 61791c0000006400650076006900630065005f007400790070 00650000000f0000004e5644412c506172656e74</string>

The result:
- Installation: success
- Boot and Shutdown: success

- Graphics: working, but very poor, no acceleration at all
- Sounds seemed to not work
- LAN: failure
- Wireless: I have removed my Wireless because I didn't like it, and it is causing a lot of hick-ups on Windows 7

If anyone knows any ways to fix any of these problems, please let me know.

Thanks.

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