Please read the complete tutorial and ask any question you may have on the OpenEtna Forum prior to proceed with the operation. Please also make sure that before you post a question you search the forum. The odds are your question has been asked and answered. 

Determine if you have a rom that has fastboot. To do this power off the LG eve. Open the Keyboard  and plug in the phone. As soon as you see the back light of the screen turn on press the space bar. If you have Fastboot you will see a screen that looks like the following. Windows at this point if you have connected your phone will ask for drivers. Point the new hardware wizard to "C:\Program Files\OpenEtna win Flasher\usb_driver" 

 If you got this far continue to step 3. If you were not able to get a fastboot screen see recover fastboot below.  

If you have installed LG official v10I, v10N or some other version that does not have fastboot, you should downgrade using KDZ_FW_UPD. More details on this software can be found on the XDA forum (here) A translated tutorial can be found here.

I have not personally had to do this but if you have any problems again the OpenEtna Forum is your friend.

Image with fastboot for 900 Mhz 3G:

If you have not yet done a backup of your original firmware I suggest you do it at this point by clicking the Amon RA recovery button wichloads the Amon RA recovery on the phone. You will be able to create a backup using the volume keys and the camera button. The image will be saved to your SD card so please make sure that your SD card is properly mounted.

You will now need to download the latest Boot and system images at the link below if you have not yet done so.

Unzip the System and boot files somewhere safe.

You will see a prompt to select your System image file. Click ok and select it in the file selection screen on your pc. This will be followed by the same procedure for the boot file.

Once this is done a new screen with 3 options popup.

Select option 1 if it is your first time Flashing OpenEtna or you were instructed by someone in the forum to do a Fastboot -W

Select option 2 all other times

Select option 3 (why did i even offer to Quit you got this far your most likely not stopping)

Once you made your selection just let the software do it thing and press the space bare when asked.

When the screen shows operation complete review the screen for any errors. If you see no error reboot the phone (be patient it can take some time on the first boot) once in android plug in your phone and mount the sd card. You will then be able to copy the following  zipped file to the root of the card and reboot the phone in which case all the google apps (gmail, market etc.) will be installed (I and others typically do this before flashing the firmware wich means that on the first boot for OpenEtna it will be installed but I am not sure if this will cause any issues).