To answer your question directly the cat will not process at an optimal level when it is cold, so it is damaging.

Better than letting it idle to operating temp and really the only logical option but damaging none the less.

 

While there is no question that catalytic converters don't operate at full efficiency until they're up to operating temperature, I've never heard cold engine operations are in any damaging to the cat; can you please provide some technical references supporting this, I'd love to read it/them.

 

"The problem is, letting your car sit and idle is the slowest way to bring it up to operating temperature because it’s generally sitting in your drive at just above idle speed. And this method to warm up also invites other problems. Remember that modern cars are equipped with a multitude of devices to help them run clean, including a catalytic converter (sometimes three of them), a device in the exhaust system that works to burn off unburned hydrocarbons in the exhaust stream. A cold engine emits a far higher percentage of unburned hydrocarbons than a warm engine. Unfortunately, the average catalytic converter can’t process 100 percent of unburned hydrocarbons even in the best of times. Importantly, the catalytic converter needs high exhaust temperatures to work properly. Throw in a cold engine emitting a high percentage of unburned hydrocarbons, repeat several hundred times, and you can end up with what’s called a “plugged” converter. In a nutshell, the converter becomes overwhelmed and literally ceases to function. This won’t happen all at once but over time, the end effect is the same: poor mileage and significantly dirtier exhaust."

— Richard Backus, editor in chief, Gas Engine and Motorcycles Classics magazines

I think you are taking what I said too literally, what I am saying is that it is more damaging to idle to warm up but there is no denying that until the cat is up to temp and the engine is warm the amount of hydrocarbons going through the cat will be higher. This is considered wear and tear. Which still happens when you are driving, granted it will get the cat warmer faster and is a better method than idling to warm up.

Short of an electrical plug in heater for your cat (which would be insane) there is no way to mitigate this. In conclusion as I stated earlier I agree that the best way to do this is as you suggested start up and drive away. <1 min of warm up is all that is needed any more and you are unnecessarily damaging your cat. I don't know what else you want, I'm sure I could dig up some extend emission test but I don't see why that would be necessary.