Rehearsal mark number

[Jérôme Plût]

Is there a way, from within Scheme, to access (read/write) the following:
 - the current rehearsal \mark number;
 - (optionnally) the current value of Score.markFormatter?

The reason I am asking this is that I am typesetting a score where the
mark J *and K* are skipped (I guess that this is because of Italian
foundries not having this letter in their alphabet, but that's a
digression!). Instead of defining a new format-mark-letters-but-K
functions, I would prefer being able to manually set the mark number
(this would be applicable to more cases!).

Thanks,

-- 
        Jérôme