There've been several threads on this before, complete with discussion on the Louisiana Purchase, the Sedition Act, and the survival of the Federalist Party. PoD's proposed are generally in either the state legislatures or the Electoral College. Long story short: not that hard at all, but the consequences are disputed.
EDIT: I just wrote a page in the Wiki on this, with an index of all the threads that I could find about the Election of 1800.
SECOND EDIT: Oops,
here's the correct link. Thanks, CT23.