Was the 'Customize Theme' option taken out? I need to edit the CSS for a theme.
As far as I know this has never been in the OS version.
You have 2 options:
My themes: pure | minusbaseline - My plugins: CSSedit | HTMLedit | InfiniteScroll | BirthdayModule | [all] - PM me about customizations
VanillaSkins.com - Plugins, Themes and Graphics for Vanillaforums OS
Are you on hosted? In which case you asking in the wrong place.
grep is your friend.