cant seem to access the service menu to overide gps so can be used while in motion to set new location ect. any tips?

thanks to the user for his input on the steps. the keys are first go to dvd tab not volume then do the lexus technician tap dance left top bottom left tap corner screen 2x then bottom right press an hold your in the top secret rice fields hold the overide 5 secs till beep. then tap back to get out.