ETHANOL:
"I worked as a molecular biologist for years and learned that straight
up ethanol or isopropyl alcohol (rubbing alc) will remove ink. I have
used it on other cars w/leather seats to remove pen stains, and it
didn't damage the seat at all. Still I would try it in a small area.
But I guarantee you if anything will remove the stain, ethanol will.
And it is way cheaper than anything else."
http://www.350zforum.com/net/viewmsg.aspx?forum=technical&msg_id=3428