Anyone done this? Any tips or tricks, or should I just hav ethe thing rodded out?

having it rodded out would be safer.

Yep it can be done. I've cleaned out a radiator and a couple of heater cores with it but it was a pain. I would put a few cups in a removed radiator with all the openings plugged. Swish it around for a few minutes and dump it out in a safe acid proof container. Then I would pour a mixture of baking soda and water in there and repeat the swishing until the acid was neutralized. Don't get the crap on your skin, it is the same as the stuff in your stomach, very nasty. Baking soda is your friend! Make sure you get the acid neutralized or your radiator will be swiss cheese. Taking it to a radiator shop is much easier. Let someone else deal with the mess!