This is possible! Your Partners can add &orid=<Their Contact ID> to the end of any URL to turn it into a promo tool. In order to enable tracking the page they are sending contacts to must have the ONTRAPORT Tracking Script installed (it is installed by default on all ONTRAPORT landing pages and integrated WordPress sites).
Because you haven't created a separate Promo Tool, you will not have complete statistics on their efforts. But every opt in or purchase will be credited to them.
If you want to send instructions to Partners in an email, you can use this text and the [Contact ID] merge field to automatically fill the string with the correct Contact ID number: