You can add both a checked and click binding to an input. However, you would want to return true; from the click handler. This will allow the default action to proceed (the checkbox will be checked/unchecked).
Here is a sample: http://jsfiddle.net/rniemeyer/cnkVA/
An alternative technique is to push this logic into your view model and subscribe to changes to a boolean observable and execute your action like: http://jsfiddle.net/rniemeyer/cnkVA/2/