Those links are for 2nd generation IS.
For the IS300
1. locate light gray cap on headlight, turn cap a few degrees clockwise and pull off. (the cap is the big circle with the wings on it in the diagram and it's sealed with a reusable rubber "O" ring.
2. turn socket clockwise and pull off
3. unclip bulb (two clips, one on each side of bulb, unclips at top)
4. remove bulb and install new one then reverse the process to finish
the light gray cap and the socket have arrows on them to tell you which way to turn to lock. the clip is little more than a thin metal rod bent to retain the bulb on both sides. iirc you push it out away from the bulb to unclip it. the metal fishing pole thing on the bulb will be the bottom. small hands are good for this job. my hands got some nice scratches and scrapes. remember to not touch the bulbs , if you do, clean it with isopropyl alcohol (rubbing alcohol) and a qtip, make sure no fibers from the qtip remain on the bulb. I started on the passenger side as the threads I found in my search[]/b] suggested. It was easier and since it was my first time, helped a lot that I started on the easier side so I knew what I was doing when I got to the harder side (cramped driver's side)
* You can remove the intake, airbox, and or move stuff like the washer fluid filler neck, to help gain access to the headlight caps.
IS300_Headligh_adjustment..pdf