well...i did try to install WP-United. the installation went smoothly...at least according to the setup wizard that was made available via my phpBB ACP.
the trouble i had was that i was getting database errors as soon as i tried to access my blog through the new portal set up through the phpBB Mod.../forum_root/blog.php.
as i tried to find an existing solution in the WP-United forum and the phpBB Support Forums, i found that the developer has not even logged into either site since December of 2007, seemingly abandoning the project and offering no further support. so considering that there would be no more updates or further support, i decided to uninstall the Mod and begin searching anew.
its a shame really. it had gotten alot of raving reviews from the phpBB users who had installed it. it did seem to be far more complicated than what i needed, but it is the only thing that i have found that offers ANY kind of phpBB/WP userlist sharing.