Note that, on my computer, after issuing the adb sideload command to flash LOS, the % tally stops at 47%. It just sits there like that for a long while with occasional text popping up on the phone. You have to be patient, it will complete. Make sure you reboot to recovery after you have flasjed LOS.
Also, when you try to sideload Gapps, recovery will complain and ask if it is safe (it's some signature problem I think). Just say yes.