Steve,
Sorry, I should have been more clear and wasn't aware there is a separate EMS installation manual.
The full Dynon manual can be found at this link.
http://dynonavionics.com/public_html/yabbfiles/Attachments/SkyView_System_Installation_Guide-Rev_AD_v15_3.pdf
The above link will only work for the current version. For future readers, the documentation link is:
http://www.dynonavionics.com/skyview-documentation.php
As depicted in the manual, you'll want to power both units from pin 15 of the EMS-220, which will keep the units working if you lose ship power and are relying on the Dynon battery backup. If you have a different battery backup configuration, you'd want to power them from that solution.