As it happens the info field for the Title and Category will be available in 6.17. In that version we have made major changes and moved the Joomla fields to the field manager. This has allowed us changes including adding the info field.
Currently you can add an info tag using override but it is more work... so if your client can wait a little.
We are currently testing upgrading from 6.16 to 6.17 and have to do this thoroughly. I expect a beta release at the end of next week.
Please read the F2C documentation before asking questions! Thank you if you've done so