lp-ssh-add.sh

#!/bin/sh
#
# Import all SSH keys from LP
#
PREFIX=~
SSH_ASKPASS=$PREFIX/bin/lp-askpass.sh
export SSH_ASKPASS
# This is needed to force ssh-add to honor our SSH_ASKPASS.
DISPLAY=foo
export DISPLAY

CONTAINER="Secure Notes\SSH"
# For some reason, lpass ls includes the folder's ID
CONTAINER_ID=4532168026

for key_id in `lpass ls "${CONTAINER}" | grep -v $CONTAINER_ID | awk '{print substr($4, 0, length($4))}'`; do
    KEY_ID=$key_id
    export KEY_ID
    # setsid is needed to force ssh-add to honor our SSH_ASKPASS.
    $PREFIX/lpass show --field "Private Key" $key_id | setsid ssh-add /dev/stdin
done

lp-ssh-askpass.sh

#!/bin/sh
PREFIX=~/bin
if [ -z "$KEY_ID" ]; then
    exit 1
fi

$PREFIX/lpass show --field Passphrase $KEY_ID

So I can't use the Private Key / Public Key fields because of https://forums.lastpass.com/viewtopic.php?f=7&t=94925 . The problem is that if you use the web UI, you can paste the full key in but it converts all carriage returns to spaces (thus corrupting the ASCII-armor). If I use lpass edit to edit the field, it only saves the first line. These 2 fields need to be made multi-line to be useful.