Upload to nuget server behind invalid SSL / self signed SSL

We have an installation of Octopus Deploy Server and are using the inbuilt nuget package repository. The server is available by IP address only using a self signed certificate for HTTPS. I have configured it to accept both HTTP and HTTPS connections, but want to disable the HTTP connection.
The problem is that we are using nuget.exe to push packages to it from a local continuous integration build. However, this is only working when using the HTTP url. HTTPS fails with a TLS error due to an invalid certificate.
There was an indication that octo.exe could be used to upload to the nuget repo and I know this has a command line switch to ignore SSL errors, but I can’t find the functionality to upload nuget packages using octo.exe. Does this exist?
Discussion: http://help.octopusdeploy.com/discussions/questions/2258-push-a-nuget-package-to-the-octopus-server-automatically - refers to a page which uses msbuild, rather than octo.exe - though i imagine it uses octo.exe under the hood?
Alternatively is anyone aware of any way to coerce nuget.exe into uploading to HTTPS with an invalid SSL certificate?

Hi Claire,

Thanks for getting in touch. Unfortunately, octo.exe doesn’t support pushing packages to the Octopus server. The solution is to add your self signed certificate to the Octopus server’s certificate store. We have documentation on how to do this at the following URL.

The “Importing your SSL certificate” section describes how to do this.

Hope this helps!