How I got mount_psshfs(8) to work.
mount_psshfs basically offers the same functionality as sshfs(1). Putting it to work is quite easy but it is not enabled by default, so some work is required.
0) Set up ssh keys
1) Build, install and boot a new kernel which includes the following parameters. Here is how.
pseudo-device putter # PUFFS(4)
options PUFFS #Pass-to-Userspace Framework File System
Alternatively, just load the module
2) Add device rules in /etc/devfs.conf
perm putter root:wheel 0666
3) Enable vfs.usermount
In /etc/sysctl.conf add
4) Mount it!
mount_psshfs -O IdentityFile=/home/earthling/.ssh/mercury_rsa firstname.lastname@example.org:/Users/mercurius/export /home/earthling/mnt/remote_to_mercury
mount_psshfs: handshake failed, server does not support sftp?
mount_psshfs: puffs_mount: cannot open /dev/putter
mount_psshfs: puffs_daemon: Permission denied
mount_psshfs: puffs_mount: Permission denied
mount_psshfs: puffs_mount: Operation not permitted