I'm installing the risers on my 2008 with Navi. Instructions and "dash removal" videos I've found don't really mention the Navi screen but it looks like it may need to be removed. True? I don't think the top cover can be removed unless you do.
The dash assembly, be it NAVI or not, is unbolted all the same. Basically the dash cluster is mounted with 4 bolts. Be sure to have a magnet handy, so that you don't loose a washer. Once the 4 bolts are out, slide down a little on the cluster assy., and then flip it up towards the visor. I often tie it up high using the vent as a tie point.
I'd guess they remove the dash cluster to access the stay bracket that secures the brake hoses, and wire harneses as they route over the top-bridge.
Oh ... for access to the screws for the black plastic fork brace, turn the bars.