Ya can’t.

Well, OK, you can force it by using ‘.php5′ as the extension for all the PHP files. This works if you’re writing all your own shit but not much cop if you’re installing scads of downloaded ‘.php’ files.

What bollocks. Dreamhost makes it easy in the web panel - you simply select whether you want PHP5 or PHP4 as default for a particular domain. (Current options being PHP 4.4.7 or PHP 5.2.2)

And while I’m on the subject of figuring out why my DOMDocument wasn’t working, 1&1’s documentation blows compared to Dreamhost’s combination of support Wiki and forums.

Wordpress auto Posting Website script [ php ] US $0.01 (1 Bid) Auction Ends: Wednesday Aug-20-2008 16:25:24 PDT Bid on this Item   | Watch this Item