Install adb and fastboot using pacman -S android-tools
Download Lineage image and TWRP recovery for your device.
After enabling debugger options, copy these files using:
adb push lineage.zip 'data/local'
adb push twrp 'data/local'
Put the device in fastboot mode using adb reboot bootloader. Then run fasboot flash recovery twrp.img to flash, and then fastboot reboot to reboot.
Boot to TWRP (how?). In the TWRP interface, browse to lineage.zip and hit Install.