Brian, (it must be something about you) - funny thing , we just purchased a 2.75 hp cyclone vac /blower for doing closings! (I had never heard of Cyclone vacs prior to this). The 2.75 hp should have more than enough power to do your pool.
As for the 'special attachment', I don't know if they're sold, we made our own. It's a regular superpump lid that we drilled a 3" hole in, using the hole saw we use on our pools to add extra suction and return lines. We then put an AG pool return fitting in the hole and screwed in a SP1091-Z-7 backwash adaptor. This should be pretty much what your pool dude used. With the multiport on 'recirc', you should be able to blow all the lines, though you may have to play with the valves a little to get the pressure right. As this is something you won't need til next year, do some more price shopping to hopefully reduce the cost some. Have a great winter!