listing posts in certain categories from old to new?

hi, i have a website (www.squattheplanet.com) where i have multipule authors and i want ONLY the categories “StP Chapter 1” and “StP Chapter 2” to list the posts from the first posted to the last instead of vice versa. this is for readablity purposes, as id like the reader to start from the first story in the chapter instead of the last :). i want all the other categories to list as normal. is there a way to do this? i can’t seem to find it in the codex.

thanks!