ddslick non-selectable-group options

Hello,

Is there a simpler way to have non-selectable group options within the ddslick ddown list? Or to disable certain items thus work as options group?
so ddslick creartes sth like
ul
li
li
li
ul

and I want to disable click event from certain 'li' item within the 'ul' element?

Thanks in advance!
Mokhtar