For example, this htaccess code will redirect everyone to twitter except for your IP address:
Code:
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{REMOTE_ADDR} !^12\.34\.56\.78$
RewriteRule ^.*$ http://www.twitter.com/ [R=302,L]
</IfModule>
Just enter your IP (which will not be redirected) and your twitter URL.