Step 1: In Preferences > Menu

Place the item located at

Actions > Behaviours > Activate Exposé Behaviour

from the "Item Library" to the place of your choice in your custom 
menu profile.

Step 2: In Preferences > Mapping

- Map the play button to the Dashboard action

- Map all other buttons to the action "Behaviours > Deactivate current 
Behaviour" (as found in the popup)

After that, you can enter Dashboard by selecting the item in the menu, 
then pressing Play for as long as you want to see Dashboard. Any other 
button presses will return you to the Behaviour Remote Buddy 
automatically chooses for you.

Best regards, 
Felix