BAM, could you post a daytime photo of your tail light lenses?
On the surface it looks like the same shape, just not as many lights on yours on the trunk/boot side as in US. If the the backup lights and turn signals/repeaters are the same I would think if you wanted and were skilled you could make the change. Wiring might be just simple harneses that match up with no splicing. You would have to get an installation/electrical schematic of both to be sure. In another lexus forum many people get parts from http://lexus.sewellparts.com/.