User groups in checkboxes (instead of drop-down)

Hello,

It has been two weeks that I've been trying to find the anwser for these question:
Is there any way to change the dropdown list to a group checkbox when editing a user in Community Builder 1.9.1? Just like it is in the jommla 2.5.19 core User Management.

I've read the API, the whole forum, stackoverflow... but no answer.

Can any one indicate a way?

Thanks!!