[kh99]

Do you mean plugin hook or template hook?

For plugin hooks, you'd create an xml file named hooks_something.xml (replace the "something" with some unique identifier) and put it in the includes/xml folder. To see the required format, look at one of the existing "hook_" files. Then you just need to insert code like this where you want your hook called:

($hook = vBulletinHook::fetch_hook('my_hook_name')) ? eval($hook) : false;

and obviously you'd change 'my_hook_name' to whatever you choose to name each hook.