ok just to show you how this would be done. Basicly add something like this to your htaccess file
RewriteEngine ON
RewriteRule ^forum(.*).html http://path/ultimatebb.cgi?ubb=forum;f=$1 [L]
now accessing ubbcgi/forum1.html is exactly the same as
http://path/ultimatebb.cgi?=forum&f=1 but you might want to put the htaccess file in an other folder (board, forum etc.)
for this exemple in public_forum_summary.pl
find and replace:
<a href="$ULTIMATEBB?ubb=forum;f=$x">$ForumName</a>
by
<a href="$vars_config{CGIURL}/forum$x.html">$ForumName</a>
and voila
This is a not a hack just an exemple, I know that I am not taking the accelerator into accountthe guys addon does not require editing because basicly instead of calling the ubb I suppose he calls the php script which gets the data and then feeds it.