Hi,
At this stage Domino 8 isn't officially supported on the current versions of BES 4.1 (Full support will be in BES 4.1.7). Below I have posted the IBM FAQ from their website regarding this compatibility:
IBM - Support information for RIM's Blackberry Server (BES) for Notes/Domino 8
If you still want to use Domino 8 you will still have to install a functional Domino server onto the BES. Also at a minimum you have to upgrade to BES 4.1 and use a minimum of SP6 until SP7 is released.
Thanks,
Gary