J.C.
The Queen of Clean says to use cuticle remover to get ink off of leather. Here are her instructions:
Dab a little cuticle remover on the spot and rub gently with a soft cloth, wipe and buff. You may need to allow the cuticle remover to sit for 10 minutes or so before rubbing for difficult stains. Reapply if necessary.
She also suggested rubbing alcohol. I hope you get it out-good luck!