As a builder who has removed lots of frozen seat posts over the years, I would urge caution! Always save the frame ! Don't worry about the post! They're cheap!
Do as Dale,or maybe Sheldon suggested, but don't overly stress the frame!!! Quit early and seek professional help if need be. I can tell lots of stories about wrecked frames that have shown up here after the American Tourister Gorillas [classic content] finished with them.
I've had great luck using an air hammer/ chisel with a blunt chisel under the saddle support part of the post. The vibration and the hammer blows do wonders![I can hear the howls already!] If this doesn't remove the post easily quit while you're ahead!!!
I cut the post off close to the seat lug, and take the 'magic saw' and make several cuts through the post and collapse it and slide it out. This is a horrible job that takes patience... When its not going well walk away and come back later. You saw by hand, pay attention to the sound and the feel of the blade, you avoid cutting into the steel tube. This takes time, patience and determination, is expensive but the frame is worth it.
However you go about it,don't over do it!! Think about the stress being applied to the seatstay caps etc. Quit early, walk away and think of some other method that may be less stressful to the frame. And by all means try the air hammer/chisel! Have the shop mechanics all line up and when the post goes flying out of the frame and into the air, they can all fight to see who can catch it!!! Shop Olympics/ its a whole new sport!!!
Good luck from Peter Weigle In Lyme Ct. where the only 'stuck post' was my mailman in the snow yesterday!