I would rent or buy a gantry and a set of chain falls to lift it out if the steps can be removed.http://www.harborfreight.com/1-ton-telescoping-gantry-crane-41188.html#.UyW9C86S4vk
If the steps can not be removed, a chain come along and some 2 x 8 planking should be able to drag it out of the basement.
With the come along method you need a secure attachment point for the come along.
I have a tripod that I use for lifting and I am looking at building a small portable gantry for getting stuff out of basements.
The come along method is the cheapest but that is also the most work,
To lessen the sliding resistance build a sled to go under the sections and than use the sled to transport the boiler section to the door. Either with pipe rollers or brute force.
If you can not get a truck to the Bilco door than a wrecker will not work.
Just remember keep everyone out of the way of the load with either of the methods. Gravity here is working against you.
Use chain or good lifting straps for the rigging, not rope.
Good luck. and pictures would help.