Script need PHP4 to run!!

[pegasus3009]

Site: http://www.vnpet.com
URL error: http://www.vnpet.com/login.php?game=1
test account:
user: talata
pass: 123456
All members and I login although we typed right password. I think script
could not set cookies so we could login or register.

I saw document that Script Provider sent me, he said a caution about Requirements of my script:

"PhPlug.com vPet Engine V2.2 Installation Guide

Firstly, you should make sure your computer or hosting company support php 4.0 upper (e.g. php 4.4), MySQL and Zend
(This script is tested not working on PHP 5.0 as I wrote this, PHP 5.0 has a huge different from PHP 4.0)"

Because the script needs PHP4, not PHP5 (default). So I think I should change PHP5 to PHP4. But I don't know how to do it. Can anybody do it for me?
Thanks.

[JPC-Veena]

Assuming you are on a vps, please open a support ticket from your client area at jaguarpc.com and we can downgrade php for you.

[EuroNut]

Site:Because the script needs PHP4, not PHP5 (default). So I think I should change PHP5 to PHP4. But I don't know how to do it. Can anybody do it for me?
Thanks.

I would also be getting concerned about making the script work under PHP5 before PHP4 goes away forever.