I am installing a new toilet. The original construction had a sub floor, which has been removed by the previous owner. Rather than properly seating the flange on the concrete floor, he put tile grout under it to compensate for the wood sub floor that was removed. The old toilet was sitting about 1/4 inch off the existing floor, with concrete under it to hold it up.

A lead sleave with a collar is fit into the flange, and extends down about 6 or 8 inches into what looks like a copper pipe (it's green) and that turns into a cast iron pipe further down. They're all 4''. This must be original, since it covers the flange so you can't access the screws that hold it down (although there weren't any holding it down).

I live in an apartment building, so I can't access a craw space. If I don't fix it right, I am sure the neighbors will be angry about the stain on their ceiling.

After calling Home Depot, they said: "sure, just pull that out and we have tons of things you can fit into the pipe." So I started mangling the lead sleave, trying to make it smaller so it would slide out of the copper/cast iron pipe. It now appears that it will not come out, probably it's soldered in? I have hammered it back to almost round.

Is there something I can slide into the lead sleave, or is it possible to remove it? The new flange would have to extend at least 4'' into the lead sleave - above that I have damaged it. I was thinking one of these:
Closet Flanges, abs flanges, pvc, flanges, brass flanges, bulk flanges, wholesale plumbing supplies (http://www.uapinc.net/WebPages/Plumbing/Toilet/ClosetFlanges.htm)
At the bottom of the page, item #40096, the Push in Repair Flange.

Any ideas?

"After calling Home Depot, they said: "sure, just pull that out and we have tons of things you can fit into the pipe."
just one more reason not to take plumbing advice from big box salespeople.
That push in repair flange would be just dandy with anything else but a lead raiser. The repair flange works by compressing a "O" ring against the closet bend raiser. This means it has to have a ridged surface to compress against. Lead doesn't fit that description.
By destroying the lead raiser you have narrowed you options down to zip.
Had you left it alone we could have worked something out but now you're faced with having to inform your neighbor that their ceiling will have to be opened up so the drainage can be replaced back down to the cast iron pipe. I strongly suggest that you convert to PVC from the cast iron on. Good luck, Tom

The lead pipe is pretty thick and stiff actually. You'll probably cringe at this, but here's what I have done: I straightened out the lead pipe so it's 95% of it's original shape, with a few dings from my body work tools. There was one hole in the lead about 2'' down from the floor. I put the insert into the pipe and screwed it down so it was really tight. I measured where the rubber ring was in reference to the bottom of the plastic insert and then removed it.

It didn't deform the lead pipe - after removing it everything looked OK. The lead sleave is proably 1/8 thick. In straightening out the lead pipe, the hole seems to have disappeared but I know it's still there. The rubber ring sits below the hole in the lead so it shouldn't leak, but just in case I used some JB weld pipe repair stuff on the suspect area. It should never get wet, but if it does it shouldn't leak. This is the same stuff I put on holes in gas tanks and it hardends and seals amazingly well. The plastic flange insert was put back in the lead pipe, tightened, and then I used a sealant around the bottom of it.

The smallest opening is on the toilet - about 2 1/2''. The plastic insert is 3'' and the cast iron pipe is 4''. The only way the lead pipe should get wet is if the 4'' pipe was plugged and water backed up all the way to the toilet. This seems unlikely since it's the largest part of the system. Even then the water has to get past the sealant, rubber ring, and JB weld pipe fix.

I still have another bathroom to do and it's probably the same setup. What do you suggest I do on that one to lower the flange down to the floor and deal with the lead pipe that has a collar sticking 1/2'' above the floor?

Thanks for the advice.

What about cutting off the lead sleave at the joint and using one of these: http://www.tylerpipe.com/submittals/soilpipe/ty-seal.pdf and then attaching a flange to the new plastic pipe extending upwards?

I also thought about cutting an access hole through the floor big enough to get my hand through and then using one of those rubber boots with pipe clamps. I could reach in to tighten the clamps with a screwdriver, attaching the old cast iron pipe to a plastic section going up to the flange.

OK! So if you're sold on using the lead raisers using compressions such as a flange that wiill expand against the lead or a rubber gasket that uses expansion t6o secure one pipe to another just ain't the way to go about it. As you've found out lead is not what you might call a ridged metal. It gives under pressure so it will not tolerate any type of strain.
You got a old time plumber that remembers working with lead pipes and closed bends. Don't sweat the flange. If you haven't tore up the other toilet let me tell you how we set toilets when there were lead pipes and closet bends and no closet flanges.
First off a closet flange only purpose is to secure the bowl to secure it to the floor. Nothing else! It dors not prevent leaks.
Here's what you do, cut the flange off as close to the top of the lead pipe as you can. Now, very carefully, start to flare the excess lead around the open opening down to floor level.
You will need to purchase two wood screw type closet bolts and a small can of plumbers putty. Set the bowl over the opening where it will set and mark the holes where the closet bolts will go into the floor, (if a tile floor, drill 1/4" holes and use plastic inserts to screw the bolts into. Make a rope of putty about 1 inch thick and set it over the lead flare. Screw the closet bolts into the floor. You are now ready to set the bowl. Pick it up and set it over the flare. Give it a little twist to seat it and tighten the closet bolts. Now take some Dap White Tile and Tub Caulk and grout the base for a professional looking job and give yourself a pat on the back. You've just set a toilet the way we used to set them in the old days. Good luck and if you have questions I'm as close as a click. Tom