Thanks for the support. It definitely was not referenced in the movies I checked. Breathing superheated air should do nicely for the lung searing. I have Darth Maul hack one limb off already. The others could easily have required amputation or even been fried off as his force bubble collapsed slowly ever so slowly.
Oh wow, that's a nasty image there. The bubble slowly recedes to the point he can't keep all of his arms and legs inside it, no matter how much he tries to curl up. Bit by bit, they start to burn off, starting at the ends.
As the bubble shrinks, the air within it gets hotter and hotter and slowly his lung function begins to degrade. I imagine by the time he's offering allegiance to the Sith, he's rasping and gasping and generally a mess.
If you want to generate sympathy for Vader in TTL, you're going to get it--all he did was experiment a little bit with the Dark Side (using it to kill a dangerous, evil Sith Lord no less) and kill Jar Jar in quasi-self-defense.
In the movies, Vader killed a bunch of kids and then choked his very pregnant wife into unconsciousness. Hard to get sympathy for him after THAT.