It should still be pliable. There also may be adjustment rings around where the pipe exits, now. If so, you may have to cut a ring out for a larger pipe. I'd try it without cutting anything first.
The boot is not leaking, now, right? Don't gob on any sealants, and don't remove it. The pipe will self seal in the rubber boot. If you cut it, just make sure it leaves a really good, snug fit for the pipe.Do I need to get bunch of chemicals, or just scrape off the old stuff as best I can and smother it with new sealant?