Trying to avoid including wp-load.php

I am working a plugin where I am trying to connect an HR system with WordPress. There is an XML API on the HR system so I have written the plugin to take the data and put it into a WordPress database table specific to my plugin. This is all done via the built in AJAX etc but there was a request for the person to be able to schedule a task so that it wasn’t querying the HR system on every site visit (the list of positions need to be displayed on the site front page). Then the problem becomes syncing. This is an IIS environment so they want to use Scheduled Tasks to sync the site. I explained the WordPress scheduled task API but they prefer to have it sync manually through their own infrastructure.