The rubber seal and pipe take me very little time to pop in.
I can't imagine why hj would think it would be so hard.
I use a 2x4 on the end of the pipe and a hammer. A couple of taps with the hammer and it's seated.
I normally just pull the lead out of the cast iron tee, and use a 4x3 flush bush into a insert rubber pipe donut.
I used a 4" hub closet flange with this.