Next, I prepped the area. It was pretty close quarters, so I used a fireproof blanket to protect the wall behind the pipe. Next, I laid a couple of towels under the ferrule. I spritzed everything down with a spray bottle, just to keep any sparks from igniting anything.
The rest is just patience. Fire up the torch. I used a thin tip -- the same one I use for sweating copper. Aim at the joint, and use a painters tool or similar, to scrape the lead off. It turns out, I could get most of it off just by letting it melt and run off the side of the ferrule, and onto the towel below.
After getting off most of the lead, I continued to heat the ferrule, and wiped the brass clean with another towel in a gloved hand.
Below is what I ended up with. You can see the fire blanket in the top of th epic, and the lead-covered towels in the bottom.
There was still some lead protruding from the brass ferrule. A reciprocating saw took easilly care of this.
Finally, hook up the new PVC drain with a no-hub coupling. In this case, I'm using a 2" -> 1 1/2" reducing coupling.
Just another note: Be very careful when using a torch to melt lead. A torch can ignite wooden studs, fiberglass insulation backing, and your clothing very quickly. Also, it likely wasn't needed, in addition to eye protection and long sleeve cotton clothing, I used a lead vapor approved respirator. Lead shouldn't vaporize until > 1000*F, but I didn't want to take any chances.