Install qemu and binfmt
sudo apt update
sudo apt install qemu-user-static
sudo update-binfmts --install i386 /usr/bin/qemu-i386-static --magic '\x7fELF\x01\x01\x01\x03\x00\x00\x00\x00\x00\x00\x00\x00\x03\x00\x03\x00\x01\x00\x00\x00' --mask '\xff\xff\xff\xff\xff\xff\xff\xfc\xff\xff\xff\xff\xff\xff\xff\xff\xf8\xff\xff\xff\xff\xff\xff\xff'
You will need to reactivate this every time you restart WSL and want i386 support:
sudo service binfmt-support start
Enable i386 architecture and packages
sudo dpkg --add-architecture i386
sudo apt update
sudo apt install gcc:i386
Install a x86 chroot
debootstrap --arch=i386 --foreign stretch chroot-stretch-i386
mount -t proc proc chroot-stretch-i386/proc/
mount -t sysfs sys chroot-stretch-i386/sys/
mount -o bind /dev chroot-stretch-i386/dev/
mount -o bind /dev/pts chroot-stretch-i386/dev/pts
cp /usr/bin/qemu-i386-static chroot-stretch-i386/usr/bin/
chroot chroot-stretch-i386 /debootstrap/debootstrap --second-stage
/usr/sbin/adduser --uid 0 root