As far as the camry goes, I think you can order them as a feature from Toyota (some of them come with HID projectors if I remember right), or you can pull them off the current Lexus ES. Just make sure you get all the wiring for.
As far as the Sienna, I don't think there was ever any made for that model. If you want to DIY, and you can find some hid's that'll fit, you can
use thisdj78's diy thread to guide you through how to modify the lenses (its for a gen 3 Camry, but its the same principal).
Hope it helps, and if you do find HID projectors for the sienna, let us know...there's a few of us that want to take on this project.