1) wp_phpfox login (plugin only) 

this is the workhorse of the wp_phpfox mod. This responsible for login integration and for importing users. This mod will be downloadable upon purchase as it does not require any work. this plugin assumes by default:

a) you have phpfox installed in your root directory

b) Wordpress v2+ installed to a sub directory of the site

c) Wordpress installed to the same db as phpfox

NB. the plugin file can always be tweaked if you have a different setup.

Both of the sites will operate independently of each other except that registration has to be via phpfox. However, as long as you are logged in to phpfox you will be logged in to wordpress.