Update: Added link to Francis Manapul's web site, changed his Artists Alley location
In Preview #2 I listed what I thought were the panels most likely to have Legion stuff in it. Here now are those people signed up for Artists Alley who are considered significant Legion artists; you might score a nice page from them if you hit them up early in the con.
Chris Batista (GG-05)
Dennis Calero (FF-03)
Eric Canete (II-17) (animated show artist, designer)
Seth Estrada for Ric Estrada (FF-14)
Ben Jones (JJ-09) (animated show writer, director)
Jeffrey Moy (EE-07)
Philip Moy (EE-08)
Joe Phillips (FF-10)
Adrienne Roy (FF-12) (colorist)
Anthony Tollin (FF-11) (colorist)
Also, not listed in Artists Alley but appearing elsewhere: Scott Koblish, inker on Legion of 3 Worlds. In Preview #2 he left this comment:
I'll be doing sketches of any Legionnaire, for the price of a donation to the Hero Initiative! I'll be at the Hero Initiative Booth from 6:30 through 9pm on Wednesday night at the San Diego Comic-Con. Come one, come all, it's for a good cause...
Update: Francis Manapul has his schedule up on his site, with times and locations for his signings.