Soleil on "php 4 to php 5"

Hello,

My website is running under php 4. I wanted to install zenphoto 1.4.4.5 in a folder called "photos". The path is thus: http://xyz.mysite.net/photos/ (xyz is a subdomain).

Is it possible to use zp 1.4.4.5 by placing a .htaccess file somewhere containing "SetEnv PHP_VER 5_4". I tried many locations, but did not manage so far to have zp running.

Or is there any other way to do this? I would not like to change from php 4 to 5 in "xyz" or in "www.mysite.net". Too much work!

Thanks in advance for your answers.