[Optimus One, P500, V General] Y.u.v.i:
Here is the Simple way ..try it

this link for latest working Rom >>

http://xdaforums.com/showthread.php?t=946354

how to root >>

Enable USB debugging on your phone by going to Settings –> Applications –> Development. Check the ‘USB Debugging’ option.

Make sure you have a SD card inserted and mounted in your phone (Don’t know if it’s necessary but before proceeding further I formatted my SD card after taking a backup of the data in it. Why take a risk? Smile)

Download the GingerBreak APK from XDA Developers and get it onto your phone.

Install it by browsing to the GingerBreak APK in any file manager.

Open GingerBreak from your app drawer and press the root button.

Wait for a few minutes. If there are no problems, the device will reboot itself. (The reboot will take quite some time.)

You will see a SuperUser app in your app drawer after the reboot. Open it and see if it is working.

You now have a rooted Optimus One P500 phone.

Now install custom recovery

Follow the below steps to install custom recovery on your LG Optimus One P500.

Install Android Terminal Emulator from Android Market.

Download the file "amon_ra_recovery_installer.zip" from here or here.

Check the MD5 hash value of the downloaded ‘zip’ file. You can use HashTab to do this. Right click on the downloaded file and ensure the MD5 matches 86db8a52b01f049cadb8f097a4c5bd9e.

Extract the contents of the ‘zip’ file to the root of the SD card (Don’t extract inside any folder. For example if your SD Card is mounted on J: in Microsoft Windows then the four extracted files should be right under J:/ like J:/flash_image)

Open the terminal emulator app on your phone and type ‘su’ without the quotes. This will prompt a popup on your phone from the SuperUser app asking you whether you want to give root permissions for the terminal emulator app. Click ‘Allow’ and proceed. The shell prompt will change from the previous user shell ‘$’ to root shell ‘#’ in the emulator.

Now type in the following command and press Enter. The custom recovery will be flashed on to your phone and it will reboot into Custom Recovery.

sh /sdcard/rf.sh

Shut down your phone and boot into Recovery using the Volume Down, Home and Power switch keys. You can move through the options using the volume up/down keys. Use the Menu button to select the option.

In the recovery menu, select Backup/Restore, then select Nand backup. What this will do is backup your current ROM on your SD card, if something goes wrong while flashing the new ROM you can simply boot into recovery and restore your previous ROM.

Connect the phone to your computer and inside Recovery main menu click the option ‘USB-MS toggle’ and then ‘USB-MS Toggle SDCard’. This will unmount the SD card so that you can see it in your computer. Backup everything from your SD Card. Eject from computer and toggle USB again from recovery to mount the SD card back in phone.

Though it is not a necessity for this ROM, I would suggest partitioning your SD card to create swap and ext partitions. The ext partition will come in use if you want to install apps onto your SD card later. This is different from what you see in Froyo versions of Move to SD option. Partitioning will format your SD card, so make sure you backup your SD card as mentioned in Step 3.

Go back to the recovery menu again and select ‘Partition sdcard’. Then select ‘Partition SD’. Create a swap partition of size 0 and ext partition of size 512. Once done hit Back to go again to the ‘Partition sdcard’ menu. Convert the partition you just created to ext 3 and then ext4 using the options ‘SD:ext2 to ext3’ and ‘SD:ext3 to ext4’.

Toggle USB from recovery again. Inside the SDcard create a folder AAA and copy the ROM you downloaded in Step 1 into the folder ‘AAA’ on your SDCard. Once done, eject the SD card and toggle USB again to mount the SD Card in the phone again.

Go to the Wipe option in the recovery menu and wipe userdata, /data, /sd-ext, /sdcard/.android_secure, /cache, ‘Dalvik-cache’

Then go to the Flash Zip option in the recovery menu and select the zip file you copied in Step 6.

Sit back and relax while the zip is flashed. Once recovery shows that flashing is complete, reboot phone from recovery. The first boot will take quite some time.

Enjoy Gingerbread 2.3 on your LG Optimus One P500.