Find the checkmark glyph you want to use. (Character Map or a similar font utility). Leave the utility open.
In FM, open Character Designer. Specify the chosen font, size, etc. Add it to the catalog as a new format. (the global menu commands)
Open the Para Designer, Autonumbering field. In Character Map, copy the character you want. Paste it into the Para Designer field. It'll probably come in as a letter or number. Add a tab or whatever other building blocks you want. Paint the field with the new Character tag, which should also be listed in the building blocks.
Add to the Para catalog and you're done.
Art