We're creating an XML API for Joomla that allows partner sites to create new accounts for their users on our website.

We've created a standalone PHP script that processes and validates the API request, but now we need to actually create the new accounts. We were originally thinking about just doing a CURL call to submit the signup form, but we realized that there is an issue with the user token. Is there another clean way to create a user account without going into the guts of Joomla? If we do have to do some surgery, what is the best way to approach it?