AJ8809

Has anybody had experience of installation of a transceiver in an IS300h. I am intending to install the main unit in the trunk, with a remote head on the dash. Power to be taken from the 12v battery in the trunk via a relay switched from an "accessory" supply ( still to be found) and antenna to be glass mount on rear glass ( subject to testing due to rear glass heater) Is there a convenient accessory supply or is the only one available in the centre console? Comments welcome