Hello,
As my colleague supposed, it might be possible to use a URL with the parameters, however, he wasn’t able to verify that. Looking into the mentioned answer on StackOverflow, I believe that it’s outdated by now - after all, it was posted in 2013. That answer suggests the usage of Datastore Admin and Task Queue API - both options have been deprecated since then.
Nevertheless, in response to your question, the documentation for the parameters of the taskqueue.add() method can be found here. However, please note that It is now recommended to use the managed export/import service instead.