The Who's Who chapter does have an entry on Cowl.
I don't know if I can call what he has "stats", per se - Cowl's appearances in the novels seem to suggest he's more of an *event* than he is a character. The writeup reflects that, I think, while giving you concrete guidelines on how to handle it if he (or a similar character you might make for your own campaign) shows up.
-Lenny