potato: upgrading php4

[Toby Thain <tobyhome@telegraphics.com.au>]

Hi list,

Will someone *please* explain how I can get a more recent version of 
php4 & modules than this on my Debian 2.2-based server:
# dpkg -l |grep php4
ii  php4           4.0.3pl1-0pota A server-side, HTML-embedded 
scripting langu
ii  php4-cgi       4.0.3pl1-0pota A server-side, HTML-embedded 
scripting langu
ii  php4-cgi-gd    4.0.3pl1-0pota GD module for php4-cgi
ii  php4-cgi-mysql 4.0.3pl1-0pota MySQL module for php4-cgi
ii  php4-gd        4.0.3pl1-0pota GD module for php4
ii  php4-mysql     4.0.3pl1-0pota MySQL module for php4

*without* doing a full upgrade to woody? (this is a production server 
and I don't want to take any unnecessary risks)
e.g. I want to install a PHP-based gallery 
( http://gallery.menalto.com/modules.php?op=modload&name=News&file=index ) 
and it wants "4.0.4pl1 or more recent". Whaddyaknow, it 
*specifically* refuses to install on 4.0.3pl1.

Thanks.

Toby