User data in comments

Is it possible to over-ride the default whereby WP sets a cookie with the name/email etc of commenters (so that when they return the fields are pre-filled), and instead to have a checkbox with ‘remember personal info’ option?

And, can a ‘clear personal info’ option be provided? (I’ve seen a plugin for this but it puts the ‘clear’ link in an odd place – below the form rather than above it).