Hey Thomas :)

Why not make a little (Caml) script that would parse the command-line
(or an input file) and produce as output a file applying F to the
selected implementations ?
Parsing the command-line may not be that ugly: just define N lists, each
containing the possible values for the module Mi, so that you just have
to check that argument n is a member of the corresponding list.

My 2 cents,
Sébastien.