Yes, it is possible, but you do not want to do it. I am currently in the process of undoing it in a design by someone else.
A couple of points:
With arbitration reading one byte from RAM takes 7uS with a 33MHz xtal.
Spent days on end to find that a Keil canned function used MOVX (and of course did not arbitrate).
Found several places where the arbitration was 'forgotten'.
Had ocasional interrupt response failures because the other processor owned the memory.

The solution:
some cost, but the fastest: use a DPM
no cost but slower: IIC

Erik