Hello Sam, With Consistency group you typically add hosts that are not part of a cluster and want to the same luns.  I have checked and it may be possible, however you will need to open a support case so that we can gather more information to see if it can be done.
We have a plan to replace a cluster environment with a new one.  What we have planned to do is create the new cluster ( ESX) and share the existing LUNs until the old hosts are removed.  How can we do that?  How do we handle the LUN ID issue during two servers perform write at the same time on a LUN? Thank you   Sam Woldekiros
Is sharing a LUN between two clusters possible? If yes, how do we handle the 
LUN IDs?