WordPress (3.2) files are in <chroot-1>/apache2/virt/blog/blog
Drupal files are in <chroot-2>/apache2/virt/my/drupal
In the httpd.conf for chroot-1:
DocumentRoot /apache2/virt/blog
ServerName www.medicineyoga.com
In the httpd.conf for chroot-2:
DocumentRoot /apache2/virt/my
ServerName medicineyoga.com
ServerAlias *.medicineyoga.com
<snip>
ProxyPass /blog http://www.medicineyoga.com:800/blog
ProxyPassReverse /blog http://www.medicineyoga.com:800/blog
In the WordPress .htaccess (in <chroot-1>/apache2/virt/blog/blog)
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /blog/
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /blog/index.php [L]
</IfModule>