[emeryberger]

If you read the paper, you'll see that the attack is entirely feasible to implement by hand (we did this ourselves but do not report on it in the paper). It's a pretty mechanical process. A bit of trial and error will get the job done; it's a hell of a lot easier than most assignments.

[emeryberger]

Here's the relevant quote that speaks to your statement:

  Mossad thus defies the conventional wisdom that defeating plagiarism detection
  is difficult or requires significant programming ability. The techniques that
  underlie Mossad could be implemented manually, relying on only the most basic
  understanding of programming language principles, letting them evade detection
  by both plagiarism detectors and some degree of manual inspection...