Aya,  You cannot put what we would call a "foreign" node into the cluster (vCenter or VSAN) when we are running our own instance of vCenter.  You would need to wait for the 3.5 version and use an external vCenter for that.  Definitely not supported.
Hi there ...  I have customer thinking about getting VxRAIL .. They want to know if they can put under VxRAIL vCenter management so that they cab use vMotion for Data migration . ( in Vspex Blue ... this was not supported ) Would this be same still ? Also if it is supported ( or not supported ) please advise me for the document ( or any web site ...)    thanks ! aya 
VxRAIL and existing ESXi host