This isn't with cel ink, it's with india ink, and 
these aren't my instructions, they're Higashiko's 
(www.higashiko.net) but she doesn't come to this 
forum, so you aren't going to get any help from 
her posting, so I figured I'd point you to it.

http://pub36.bravenet.com/forum/fetch.php?
id=9745412&usernum=3087734918

She explains how she does outlines there in 
pretty good detail, and she lists all the 
specific stuff, like which pen nibs are best, etc 
etc.  If that link doesn't work, go to the one at 
the top and go to the message that says 'doing 
outlines' by Higashiko