Here is a list of commands which can be used with the EM-406:
We obtained these using the following VB program:
http://www.usglobalsat.com/downloads/GPSinfo.zip
Echoing back to yourself will allow you to view the commands being sent to the device.
We took the time to check the commands being sent to the device and here they are:
WAAS enable: $PSRF161,01*0F <13,10>
WAAS disable = $PSRF151, 00*0E <13,10>
Cold Start = $PSRF104,0,0,0,96000,237759,1946,12,8*11 <13,10>
Power Save On = $PSRF160,0300,1000,1*10 <13,10>
Power Save Off = $PSRF150,0,1000,1000,0*23 <13,10>
VTG on = $PSRF103,04,00,01,01*20 <13,10>
VTG off = $PSRF103,05,00,00,01*21 <13,10>
WARNING: You may want to go through the process of echoing back the commands yourself as it is very easy to make a mistake when copying these down.