Making Signatures Fields read only or inactive until Check-Boxes are Checked

Help received on these forums have been excellent so far so here is another question;

I have a form with multiple sections and each section had a signature field and multiple check-boxes (up to 6), is it possible to have the signature field read only or inactive until an number (up to 4 or more) of the check-boxes in that section are checked?.

I would also like to have a message pop up when if they try to sign and not all the mandatory check-boxes are checked.

Any help will be greatly appreciated.

Thanks