Official comment
You can create your own partner links. You can even tell your Partners how to do it. Combine "&orid=" and the Contact ID from their contact record and it will make the URL a partner link. This will work:
https://any-old-url-you-like.com?orid=[Contact ID]
These ad hoc links will not appear as a promo tool in your Partner Program, but they will work just like pre-made promo tools.