The notes are valid as of September 3. 2020
Get a new mirrorlist
https://git.archlinux32.org/packages/plain/core/pacman-mirrorlist/mirrorlist
edit pacman.conf
Follow instructions from Transition ... section at https://www.archlinux32.org/download/
Accept package replacement/removal when required
sudo pacman -Syy archlinux32-keyring-transition
sudo pacman -S archlinux32-keyring
Remove conflicting packages
sudo pacman -Rdd pacman-mirrors manjaro-system manjaro-release bashrc-manjaro libxxf86misc menulibre
Install Arch pacman and pacman-contrib
sudo pacman -S pacman pacman-contrib
Remove
sudo pacman -Rns manjaro-settings-manager manjaro-settings-manager-notifier
Install - fix two conflicts
sudo pacman -Syu base linux linux-headers filesystem grub sudo systemd systemd-libs systemd-sysvcompat xorg-server xorg-server-common xorg-server-xwayland --overwrite --overwrite '/usr/include/crypt.h' --overwrite '/usr/lib/libcrypt.so'
build initramfs
sudo mkinitcpio -p linux
remove manjaro kernel (remove any dependencies - like drivers - remember to install opensource drivers if necessary)
sudo pacman -Rns linux414
edit /etc/default/grub
and set GRUB_DISTRIBUTOR
to Arch32 then rebuild grub configuration
sudo grub-mkconfig -o /boot/grub/grub.cfg
Update
sudo pacman -Syu
You now have a Manjaro themed Archlinux32