Google botların genelde User-Agentinde bot olduğu belirtilir, bunu kullanarak yönlendirme yapabilirsin
Alıntı
User-Agent: Mozilla/5.0 (compatible; Googlebot/2.1; http://www.google.com/bot.html) 
RewriteEngine On 
RewriteCond %{HTTP_HOST} abc.com$ [NC]
RewriteCond %{HTTP_USER_AGENT} Googlebot [OR]
RewriteRule ^(.*)$ http://def.com/$1 [L,R=301]
apache cevabı

HTTP/1.1 301 Moved Permanently
Date: Mon, 15 Oct 2012 22:10:55 GMT
Server: Apache
Location: http://def.com
Content-Length: 289
Content-Type: text/html; charset=iso-8859-1