I am not aware of anyone doing this. From the Denso website the Iridium pn# for a 2003 v6 engine is IKH20.
Specs:
IKH20 14 mm thread, 26.5 mm thread length.
IK20 (for the v8 engine)
14 mm thread, 19 mm thread length
They both cost $ 12/ea from Denso. There is no mention of heat range.
Using iridium plugs on the v6, has been discussed here on this site but I do not think a conclusion was made.