You should be able to get the equivalent of HDS’s Universal Volume Manager from HP (not sure of their product name for the virtualization software) and connect the EVA to the XP. Once you map the LUNs on the EVA through the XP, you can use in-array replication to move the LUNs from the EVA into the XP.
We do this with our HDS USP and AMS arrays. We have EVAs, but do not currently virtualize them in the USP. We could virtualize them using Universal Volume Manager, so I’m sure HP allows the same.