[Plugin: WP Super Cache] How to not cache certain pages?

Add /about/ to the the list of rejected URIs on the settings page.

On a weirdly tricked-out multisite setup, I don’t want to cache the root-level homepage.

With my setup, is_frontpage and is_home do not work for the domain root – is there syntax for a string that I can put into the rejected URIs list? The requested URI will be simply “/”.

Because the page is essentially not managed by WP, I could set a PHP variable before the cache plugin loads – is there one that would make the cache plugin not kick in?

define the constant DONOTCACHEPAGE on the front page and it won’t be cached.

For a non tech savvy, I don’t understand what you are saying, donncha ?? Specifically what do I need to put where?

I also run a network and only want the main homepage not to be cached, so that the subsites’ homepages will still be cached.

I use the really wonderful Shortcode Exec PHP plugin to insert bits of PHP into arbitrary pages. I created a shortcode using this plugin that simply executed the following:
define('DONOTCACHEPAGE',1);
and then put the shortcode on the page I didn’t want to cache.