Custom pages to domain root

[MoB Dudditz MD]

After many attempts at providing a front end CMS bridge on the TLD,
I decided to create a custom setup.
My problem is that the vB rests in mydomain.net/forum/
and I wish to create a front end with custom vB pages at mydomain.net

Does anyone know how to pull this off?
When I create a custom page for vBulletin, it has to rest inside the forum folder for it to load.
When I attempt to put a custom page a level up within the domain root,
even when I change the include in the php, it gives me a no file exists
when trying to access the global.php

In review:
my forum installation- mydomain.net/forum
I would like mydomain.net/homepage.php to interact with vBulletin.
TY