You could uh, run it through a proxy, which will TOTALLY mask it.
You put this in your httpd.conf file, not the .htaccess:
<VirtualHost *:80>
ServerName www.abc.com
ServerAlias abc.com
ProxyRequests Off
ProxyPreserveHost On
<Proxy *>
Order deny,allow
Allow from all
</Proxy>
ProxyPass / http://site-you-want-2-show.com:80/
ProxyPassReverse / http://site-you-want-2-show.com:80/
<Location />
Allow from all
</Location>
</VirtualHost>
You can try with ProxyPreserveHost both On and Off, and testing if the images display properly and the addresses of objects show your domain instead.
WARNING: This is not legal if you do not have explicit permission from the company you are trying to show's website. Perhaps you can then just make your homepage an iFrame.
As for certificates: It can be done, see here: http://ssl-proxy.plz.re (short-url)