I had to remove a blocked washer jet this morning, this is how I got it out.
It is released from the underside of the bonnet. It has two clips on it, front and rear.
I didn't need to remove the sound-proofing from the underside of the bonnet, I just unhooked it from piece of steel that holds it up. I didn't remove any of the 8 plastic rivets either.
I ran the blue tape from the top of the bonnet to the underside, so that I would know exactly where it was.
I found an old piece of plastic (2mm thick) that was left over from a shower job and I cut a length from it. I them filed a notch 12mm across and about 4mm into the plastic. From the underside of the bonnet, I then pushed it towards where the washer jet was and I could feel that it was in position because of the notch. I pushed hard until I felt the plastic clip give way and it it popped up on the top side. The jet has two clips but it only needs one to be released, and it will pop up. You can then maneuver it out from the top. I suspect that you could also release it using a credit card but the notch let know that I was in the correct position.
When I got the jet out, I was able to file a notch that was a better fit, that's the 5mm one.
I also suspect that the main Toyota dealer will have a special tool for this.
I hope this helps someone, sometime.