two character keymap

[Jeff Rose]

Hi,
  I'd like to map two regular characters to a command if typed in 
sequence, but if not one after the other in order treat them as normal. 
 Specifically, I'd like to map 'kj' to mean <ESC>.  (This way I don't 
have to move off the home row.)  If I use the regular key-mapping then 
the first character becomes a prefix and it doesn't print.  Does anyone 
know how to do this?

The only way I've thought of is to map 'k[a-z]' to insert k then the 
following character, (probably have to do symbols and other stuff too), 
but then remap 'kj' to mean escape.  Not an ideal solution though.  Any 
advice would be great.

Thanks a lot,
Jeff