Bypass the nav input-address-while-moving lockout by:

Press the Menu button on the dash.
Press the Volume button on the screen.
Press the upper left corner of the screen. (Where the speaker icon is located.)
Press the lower left corner of the screen.
Press the upper left corner of the screen again.
Press the lower left corner of the screen again.

• On the screen that appears:
• Press the Override button and hold it until you hear a beep. The Override letters turn black in color showing it is deselected.
• Press the Back button to get back to the previous screen.

Destinations can be entered while the vehicle is moving. The lockout will remain disabled until nav power is cycled.

thanks to
http://hybridcars.about.com/od/ownership/ss/navigation.htm