How To: Domain links to language

Hi guys,

I want to setup my store with two languages: Dutch/English. Now domaindutch should point to the standard Dutch language and domainenglish should point to the English version of my site.

At the moment, I've setup it (in short):
main user account: associated with domaindutch, installation of the Zen Cart (1.3.6) with standaard language to Dutch and an english. (Works fine)

in the main user, I've added a second domain (domainenglish - own public_html dir) with a index.php with header redirect to : domaindutch/index.php?main_page=index&language=en. This also is ok and works fine!

The problem I see: when a search engine hits the site with domainenglish, the searchbot will be redirected to the domaindutch (with English version as userinterface), but domainenglish will not be listed in the search engine (I'll think).

Can someone suggest how I can solve this problem, so the two domains will be listed in the search engines?

Hope anyone has an idea, TIA,
Fos