Here is a handy object that I made per the Maxon HDRI tutorial off their site. It’s a 2 sphere version; one for the “visible” image and one for the “GI” image.
To install it just drop the file into your “Maxon-> Cinema 4d -> Library -> Objects” folder. You can then access it from the objects menu “Objects -> Object Library -> HDRI 2 Sphere”.
Here is the file:HDRI 2 Sphere
and here is the Maxon Tutorial:
Maxon HDRI Tutorial
Hope this helps.