j'ai dû pas mal bidouiller pour le htaccess sur infomaniak.ch, voici le résultat:

#found on http://www.formation-cakephp.com/12/hebergement-dun-site-cakephp-chez-ovh-mutualise
#adapted for infomaniak.ch
SetEnv PHP_VER 5
SetEnv SESSION_USE_TRANS_SID 0 
#hereafter works but no cake
RewriteBase /cake/

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
#RewriteRule    (.*) cake/app/webroot/$1 [L]
#RewriteRule    cake/(.*) cake/app/webroot/$1    [L]

Redirect /cake/css/cake.generic.css /css/cake.generic.css
RewriteRule ^(.*)$ index.php?url=$1 [QSA,L]

#original file, works well on a standard linux localhost
#<IfModule mod_rewrite.c>
#   RewriteEngine on
#   RewriteRule    ^$ app/webroot/    [L]
#   RewriteRule    (.*) app/webroot/$1 [L]
#</IfModule>