Limiting Real-Time shipping by Destination Zone
 

I would like to use real-time shipping by UPS and Fedex, but disable checkout for certain destination zones. To make it even more complicated, in a couple of zones only certain products should be disabled, but if I can't solve that part I will settle for now with disabling checkout altogether for those few locations. I saw a post about disabling real-time shipping by state at http://forum.x-cart.com/showthread.php?t=41868&highlight=ups+limit+state , but because some of the zones are cities or counties it is not really enough PLUS the file shipping/shipping.php doesn't exist in 4.5

I have tried using the debugging console on the checkout page, but I can't find any reference to destination zones among available variables. Can anyone help?