[Plugin: JSON API] Get category custom fields via JSON

Hi,
I’ve added 2 custom fields to my categories using “Category Custom Fields” plugin (http://wordpress.org/extend/plugins/categorycustomfields/).

Everything works fine but I can’t retrieve the 2 custom fields using JSON Api.

In an article page I use the following code to retrieve the single custom field (in this example: the “peso” custom field):

http://www.mywebsite/?p=63&json=1&custom_fields=peso

How can I make it work for categories too?
Thanks for your help,
E.

http://wordpress.org/extend/plugins/json-api/