Then Download the ROM Manager App in your phone via Google Play Store - Click Here
Then Enable USB Debugging via – Settings > Applications > Development > USB debugging.
Then Open the ROM Manager on your LG Optimus One P500.
Click the “Flash ClockworkMod Recovery”. This will download the ROM from the ClockworkMod. So, you need a network connection or Wifi enabled. After clicking the button, it will ask you to choose the Phone Model. Choose your phone model.
In few minutes the ROM will be downloaded. After that Reboot your phone.
Now you have Installed ClockworkModRecovery on your LG Optimus One P500.
You Can get all the News Update about this Phone [ LG Optimus One P500 ] - Here To Install ClockworkMod Custom Recovery, it is must to Root your Phone. The ROM Manager works only on Rooted Devices.