Here's what I did: I created a whole team and placed them into the L.A. Kings (while the actual Kings are sitting in the waivers list) and the captain's C was just randomly assigned to a dude on my 3rd line. Any way I can change it? The edit lines option is not much help.
I don't think so. The only thing I've noticed is that when you create a player, there's a category called "Leadership" or something like that. If your player has a big score in that, he is more likely to be a captain. My guy was given the Assistant-Captain role.
One tip - if you want to trade up at any point for better players, trade for guys with 1 or 2 points more in the "Overall" category. I have an all-star team saved with almost all the best players. If you do a draft to pick your team, choose a top player or a top goalie first and second. Goalies are nearly IMPOSSIBLE to trade in this game, even if you're trying to trade for equally or lesser-ranked goalies than the one you've got.