I think there are some issues with the wiki page for the Samsung Galaxy SII (samsung-i9100):

To create u-boot.bin, I'm instructed to use the script helpers/envkernel.sh. However, there is no helpers directory in pmbootstrap. A find for envkernel turned up empty.
Alternatively, after running pmbootstrap install, u-boot.bin should have been created. Unfortunately, it is not. Again, a find for u-boot.bin turned up empty.
Since I have run replicant on the phone ages ago, I vaguely remember having already done something like this. So maybe I don't have to do it again?

Anyway, I ran pmbootstrap install --disk /dev/sdd, which exited with this error:

ERROR: Command failed (exit code 1): (native) % mkfs.ext4 -F -q -L pmOS_root /dev/installp2

That is not surprising, since this device doesn't exist. I haven't looked at the code, but I have a guess: installp2 is the name of some internal variable that should have been expanded to sdd2 before passing it to mkfs.

Then I found pmbootstrap/chroot_native/home/pmos/rootfs/samsung-i9100.img and tried to dd that to my sdcard. Unfortunately, that didn't create any partitions on it.

Thus, I'm at a loss. How should I proceed from here? Note, I haven't even touched my phone yet.