I use a Garmin III+ and use Velcro to fasten it on the dash above the radio and in front of the clock. It works great in this location. The mount is very secure and visibility is good. I don't know if this is an option for your Emap because it may have a different form factor.
A couple of other options: 1) I've seen cell phone holders that mount to dashboard vents. This should work pretty good on the center vents. 2) You could fit a block/bracket in the compartment just below the radio (if you have one) and attach the GPS, via a strap or Velcro to it.