Avatar Plugin - resides in different directory WPMUforJoomla

Hello, My custom wpmu component for Joomla resides in
/httpdocs/components/com_wpmu
below that directory things look normal for wpmu install
The rewrite rule in the install instructions is:
RewriteEngine on
RewriteRule ^(.*/)?avatar/(.*) wp-content/avatar.php?file=$2 [L]

I tried changing it to
RewriteEngine on
RewriteRule ^(.*/)?avatar/(.*) components/com_wpmu/wp-content/avatar.php?file=$2 [L]

When i try to upload the file i get error message
" NOT FOUND The requested URL /administrator/users.php was not found on this server."

Any help getting this plugin to work with my version of wpmu would be greately appreciated...wjwjr