Hi @jack_2010
I can not write a dedicated checkbox field for you.
If you wish to create your own checkbox field, please read over the documentation which explains how to create a custom field type:
http://www.advancedcustomfields.com/resources/tutorials/creating-a-new-field-type/
May I ask why you need the data to be saved in this format? Why can’t you have it saved as a serialized array?
Thanks
E
