How to get the real IP when using Akamai?

[dangaul]

Thanks for the comment.

It's not something Akamai can help with. Akamai passes the client's IP through a different header (True-client-ip) versus the normal client IP, since akamai acts as a barrier between our site and the user.

What I'm looking for is a way in vbulletin to use the IP passed in the header "True-Client-IP".

So, normally in PHP you use:
$_SERVER['REMOTE_ADDR'];

I have to use $_SERVER['True-Client-IP']. Is there a way to do this easily in Vbulletin instead of modifying core files.