How to start gpg-agent v2.4.8 on Windows (gpg4win 4.4.1) with OpenSSH emulation?

[Marco Ricci]

Dear GnuPG developers,

how do I arrange for gpg-agent (v2.4.8, Windows, gpg4win 4.4.1) to start
with OpenSSH emulation?  (That is, how do I instruct gpg-agent v2.4.8 to
listen on the Windows named pipe "\\.\pipe\openssh-ssh-agent"?)  Per the
manual at https://www.gnupg.org/documentation/manuals/gnupg/, this
should "simply" be "run gpg-agent with the
--enable-win32-openssh-support option", but neither the manual nor the
error and help messages from gpg-agent and gpgconf are sufficient for me
to discern how to do this.

Specifically:

   - Running `gpg-agent --enable-win32-openssh-support` in a PowerShell
     window either emits "The gpg-agent is not running for this session"
     and aborts, or if the agent is started beforehand via
     `gpg-connect-agent /bye`, then `ssh-add -l` emits "Error connecting
     to agent: No such file or directory".

   - Writing "enable-win32-openssh-support" manually into
     `C:\Users\<Username>\AppData\Roaming\gnupg\gpg-agent.conf` causes
     `gpg-agent --gpgconf-test` to complain "invalid option" on the
     respective line.  Attempting to add the option via piping
     "enable-win32-openssh-support:0:1" into
     `gpgconf --change-options gpg-agent` likewise causes gpgconf to
     complain "unknown option enable-win32-openssh-support".

   - Starting gpg-agent with only the "--enable-ssh-support" option,
     which *is* recognized by both gpg-agent and gpgconf, does not cause
     gpg-agent to listen on "\\.\pipe\openssh-ssh-agent": `ssh-add -l`
     again emits "Error connecting to agent: No such file or directory".

So, what *is* the intended way to start gpg-agent on Windows with
OpenSSH emulation? And where is it documented?

Cheers,
Marco