Pretty easy.  Just generate a cert and then import it.  You can read more details here or just follow the steps below.

“If you use Internet Printing Protocol (IPP) to share or access your printers over the Internet, keep in mind, print jobs aren’t secure. However you can enable encryption by setting up IIS with a security certificate, so you can access the printer via the https address using SSL.

First you need to create a self-signed cert using IIS:

1. Open the IIS Manager from the Control Panel.
2. Double-click the Server Certificates icon.
3. Click the Create Self-Signed Certificate link on the right.
4. On the dialog box, enter a name, and click OK.

Next you need to create bindings for HTTPS using IIS:

1. On the left Connections list, expand the Web Sites, right-click your site name and select Edit Bindings.
2. On the bindings window, click the Add button.
3. Select https for the Type and choose the certificate name, and then click OK.

Remember, you need to make sure port 433 is open by your firewalls. Plus you’ll probably need to set up a port forward on your router to forward traffic on port 433 to the computer that’s hosting the printer.

Then access the printer list with https://x.x.x.x/printers (where x.x.x.x equals your Internet IP address).”