The HH-52A is sort of a hybrid of the H-19 Chocktaw and SH-3 Seaking but it will require a huge amount of scratchbuilding. It is one of my someday I'll have enough time, information and skill to do it builds.
The main and tail rotors came from the H-19, the fuselage is sort of a smaller single engine Seaking.
Schiffer has a good book on the HH-52A, it also has some info on the other versions of the S-62. The book has a ton of info on the helicopter and is not very expensive, lots of photos but unfortunately no highly detailed engineering diagrams.
http://www.amazon.com/Sikorsky-HH-52A-Illustrated-Lennart-Lundh/dp/0764317822/ref=sr_1_1?ie=UTF8&s=books&qid=1257789646&sr=8-1