extensions hassle

Hi, I am trying to find a way to switch on the GD Image Manipulation Library
. I can do this easily on my local machine, it's just a case of enabling it 
in the php.ini file. 

My problem is that I have to find a way to do it on someone else's server wh
ere they have virtual hosting and therefore cannot alter the php.ini file di
rectly - I am assuming the gd library is there but not enabled (since it is 
bundled with php 4). Is there a way to enable it using something like ini_se
t() or similar? Please help, I am very tired...

dan