Custom changes - best practise....

[pulponair]

Hi,

i am about to add php-fpm support to my ispcp installation.
Changing the apache parts wasn't a big deal but beside that i need to make changes to the php-fpm configuration file everytime a domain is added or removed.

I would like to ask you guys if anyone could give me a short walktrough of how things are working behind the scenes.
I.e.: Which part of the engine is called at what point, what files are involed, where to hook in best etc.

Of course i could apply my own hackish modification but i would like to do it at least "half" the ispcp way...

Cheers,
Nikolas