For Discovery 3/LR3 and Range Rover Sport up to 2009
This cannot be done since Land Rover never implemented it. Aftermarket kits are available.

 
For 2010 and up vehicles fitted with a FBH (not the electric heater)
IIDTool Menu->Car Config->HVAC Ventilation->

  • FBH Call Start is equal to Fitted radio.  This is the one related to the remote.
  • Fuel Burning Heater is equal to Fitted parking heat
  • Timed Climate is equal to Enable

 
For Range Rover 2002-2004
IIDTool Menu->Car Config->ATC Heat Cool->

  • Aux Heater is equal to Yes
  • Park Heater is equal to Yes

IIDTool Menu->Car Config->Instrument Pack->

  • Park Heating is equal to Yes
  • Park Ventilation is equal to Yes

Note: On 2002 to 2004, the park heating function may take up to one week before it becomes available on your monitor when activated.
 
For Range Rover 2005-2009
IIDTool Menu->Car Config->ATC Heat Cool->

  • Aux Heater is equal to Yes
  • Park Heater is equal to Yes

IIDTool Menu->Car Config->ACM Audio Control Module->

  • Park Heater is equal to Yes
  • Auxiliary heater is equal to Yes