You certainly CAN, but not without being comfortable working
in javascript. Is there a particular reason you want to use
checkboxes as opposed to radio buttons?
From an interface standpoint, its usually not a good idea to
change the expected behaviour of HTML form elements. If users see a
radio button, they usually assume that it will allow only 1 choice.
If they are presented with a checkbox, they could very easily
expect that they could select more than 1.