Go to Settings -- Office Settings
Click on Online Scheduler Settings in the Online Scheduler section
From there click on the Services tab and click Edit Inspectors next to the service you want them available for.
In the window that appears you can search for specific inspectors or check everyone off, or select individuals by putting checks next to their names, and hit save.
Note: Inspectors that are assigned to a service will only show up if their online availability is set. You can read more on that here.