What I've done when I need to do this is to place the DashBoard in the same folder as the Xpression project... Then when I first export out the xpression package .xpp, I place it in the same place.
Then after that, I write a small readme.txt and zip the .xpp and the .grid (from dashboard) together. And deliver the .zip...
Worked flawlessly so far...
However adding DashBoard to the entire .xpp sollution would be really nice...
#XPression