This is the most secure thing around but you still need to caulk or otherwise seal the tophttp://www.buildmartstore.com/retrospin.html
This is the only source I know of.
I have seen small storm collars with a slip-fit join on one side. It opens up to go around the pipe and slips back together at the opening. Those should be available at a local plumbing or roofing supply house.
There are also many fabric wrap then brush on systems available but they can't possibly be as durable as metals.
Whatever you do, post a pic and let us see what you come up with