Events+ – add an additional field, textbox, button to the post form

Firstly, I am aware that the additional fields addons that you provide are only available to the user during registration.

I would like to add a textarea/box (or other fields) to the post form. I want the value of the textbox to be posted along with the users choice of YES/Maybe/NO so all the data can be downloaded as a csv. (FYI – the textbox will ask why the user has chosen no or maybe)

I do not want to blend this plugin with any other plugin, so any information on how to achieve this within the Events+ plugin will be appreciated. Even if its pointing me in the right direction of which plugin files to amend in order to get the data posted into the database.

Thanks in advance.