The only method of creating a check box to be used in the Plug-in is to create box (or use the DocuDings font like Andy explained) and place a field over the box where the field type is set to "X or space".
This will require the user to enter an "X" opposed to simply clicking the box.
It will not work since our documents content depens from user or db inputs. You never know where such box will be on a page (at least vertically). Or I have to move field with x, every time when I creating the page (I am not sure if I can do this)