"Mount" network share as a volume via SSH?

Use HomeBrew to install fuse4x and sshfs

The commands to install are:

brew install sshfs

when you run it, it gives two other commands that I needed to run in order to install the fuse4x kernel extension. Run them.

Then, to mount the ssh filesystem

mkdir ~/mymountdir
sshfs username@hostname:/home/thedir ~/mymountdir

it will ask you for your password.

I've not tried it, but for what it's worth, the man page for the Unix mount command lists that you can connect to remote systems:

The mount command calls the mount(2) system call to prepare and graft a
special device or the remote node (rhost:path) on to the file system tree
at the point node.  If either special or node are not provided, the
appropriate information is obtained via the getfsent(3) library routines.