Faced with the same problem on my Catalina 22 some years ago, I solved it by using the jib halyard. I tied a spare line to the the shackle of the jib halyard and belayed the line. Then, using the jib halyard as it passed through the sheave atop the mast, and came down the aft side, I stood on the cabin top and began whipping the jib halyard in circles.
Took only about 5 minutes before I had snagged the shackle on the main halyard; then, it was a simple matter to untie the spare line I'd tied to the jib halyard, and pull the main halyard down using the jib halyard.
Actually wrote a little piece about this for my yacht club :-)