[LG Optimus G (International)] cjaa92:
DISCLAIMER: I AM NOT RESPONSIBLE FOR ANYTHING YOU DO TO YOUR PHONE WHILE USING ANY OF THE INFORMATION LOCATED BELOW. IF YOU DO NOT UNDERSTAND WHAT IS BEING DONE, PLEASE DO NOT TRY ANYTHING DONE HERE!

1) First of all you need is to Root your devices and unlock your Bootloader. (Belive me I tried to Customize without Unlocking BL and got HardBricked, yeah I know I've learnt by the hard way xD)

2) Make a Nanadroid Backup in case you mess up with your phone. To do it, you need to reboot into Recovery (Vol Up + Power --> After that press twice Volume Down and press Power Button. Then click "backup and restore" --> "backup" and continue.

3) Choose the rom (CRom) you want and also make sure it's compatible with your device. Do some research, in many cases the camera is the indicator if it's compatible or not (13M or 8M), any way Do some research. Download it and save it in the palce you want to work with it (I've done it all in my phone).

4) If you can get the Original ROM (ORom) from your device get it, it's better to have it, in my case I couldn't get it but I used the files from my device in "/" folder

5) Extract the CRom in to a New Folder (also extract ORom). Browse in the CRom into "system/" and find build.prop and open it with a Text Editor. Then open from your ORom the build.prop (located in "/system/" in your device or in "system/" in the ORom you downloaded) and here is the important thing. From ORom build.prop Copy the exact values of ro.product.model, ro.product.name, ro.build.description and ro.buildfingerprint and replace them in the CRom Build.prop. It's very important to replace this so your device could get the update fine. Zip it again and save it, it's ready to flash it.

6) Then you need the modem.img, try to find it in http://downloads.codefi.re/houstonn/lgog/modem (Thanks to CodeFire Team), or try to get it from Your device, The dir is "/dev/block/plataform/msm_sdcc.1/by-name/" and there will be 3 files you need to copy "modem", "modemst1" and "modemst2". If you just have "modem" copy it and that's it. Also if you want to preserve your APN list, go to directory "/system/etc/" and copy apns-conf.xml.After flashing put those files again in their places and set up the correct Permissions table (Modem lrwxrwxrwx, apn-conf.xml -rw-r--r--)

**UPDATE: Don't worry to much for the baseband , I was doing some research and found that many baseband are the same for many variants. On the back of the phone find the FCC ID which is the one that determines the baseband frequencies of the device. Google it and check which devices have the same FCC ID as yours. Then download the modem.IMG and flash it ;)**

7) Follow the instuctions for installation of the ROM, and after flashing the CRom that you've created and gapps, if you could found your modem.zip from Codefire team, then flash it.

8) And Voila! Your Custom-Custom ROM it's flashed! Wait for the first time booting and check if everithing is ok! If you're locked out of 4G/3G/2G check the APN's configuration to match with your carrier's. Hope it help you! :fingers-crossed:

**IMPORTANT** Remember to do this everytime you Update the ROM

If you found this usefull, don't forget to click the "Thanks" button ;)