There's no comments here, so I don't know if this needs an update. If you still think it'd be helpful, feel free to repost to lj_userdoc about it. :)
So I Repost!
I want to ask to add to:
My friends' comment pages are displaying in different styles. How do I change this?
"To view your comments page in the same style as your journal you need to use S2, and also must have a paid account. This is explained in the referenced FAQ. If you would like to be able to do this, you might want to consider purchasing a paid account. Information on how to obtain a paid account can be found here: http://www.livejournal.com/support/faqbrowse.bml?faqid=21
If you select the "View comment pages in your journal style?" then as a free user, all comment pages that you visit from your Friends page will show in the default LiveJournal style. If you had a paid account and were using S2 the comment pages would be in the style of your journal.
With this option deselected, then if you view the comment page of someone with an S2 style and a paid account, you will see it in the style of that person's journal.