I understand the frustration. I have been through it. :)
I installed it in like what you did. /wpmu in /public_html. Using ITDamager's .htaccess and it worked, but there was some problems. I did some modifications and I can incorporate the default .htaccess successfully.
I suggest you clean your entire system of WPMU and start a fresh. Delete all your files, including your .htaccess. If you can't, go to your File Manager in cpanel to delete it.
Then install again in the format above.
It should work, if not, then it's your Apache settings that is troubling you. Ask your admisnitrator to do this.
------------------------------------------------------
Request update BIND Zone file by
go to zone file
/var/named/yourdomain.com.db
add this at the end of above file
*.yourdomain.com. 14400 IN A 12.34.56.789
restart BIND
/etc/init.d/named restart
---------------------------------------------------------
Virtual Host setting for domain.com to be like this.
<VirtualHost 12.34.56.789>
DocumentRoot /home/username/public_html
BytesLog domlogs/yourdomain.com-bytes_log
User username
Group username
ServerAlias http://www.yourdomain.com yourdomain.com *.yourdomain.com
ServerName http://www.yourdomain.com
CustomLog domlogs/yourdomain.com combined
</VirtualHost>
Please restart all web services (apache) after modification.
------------------------------------------------------------
==================================================
In addition, I would also need access to edit the httpd.conf file. As I need
to get Apache configured so that mod_rewrite works. Here are the instructions
1. Make sure a line like the following appears in your httpd.conf
LoadModule rewrite_module /usr/lib/apache2/modules/mod_rewrite.so
2. In the <Directory> directive of your virtual host, look for this line
"AllowOverride None"
and change it to
"AllowOverride FileInfo Options"
=================================================
VOILA!! Happy good friday! :)