[TYPO3] Get variable from url to page.config ?

[joga]

I want to assign variable from url to page config because I have dynamic 
content which I want to spread to multiple pages(pics from flickr).

Variable which I need from the URL is P (page).
page.config.P = GPvar : P

How I can assign that P var to my config?

-----
This works, but there must be some other way?!
[globalVar = GP:P = 1]
page.config.P = 1
[globalVar = GP:P = 2]
page.config.P = 2
[globalVar = GP:P = 3]
page.config.P = 3
[GLOBAL]