I recently tried programming the garage door opener built into the auto-dimming mirror of a 2015 Lexus GS350. The manual provides two sets of instructions: one titled “Programming HomeLink” and a second titled “Programming a rolling code system”. I initially had some difficulty getting it to work as it was not obvious you need to follow both sets of instructions sequentially if you have a garage door system that uses a rolling code.
So first, with your existing garage door remote pointed at the mirror, you need to press and hold one of the HomeLink buttons on the mirror and then press and hold your remote until the indicator light (on the mirror) blinks rapidly. Then you need to press the training button on your garage door opener unit; now press and hold the mirror’s HomeLink button for 2 seconds and then repeat. Now the mirror should be successfully programmed to open your garage door. Here is a link to more detailed instructions directly from the GS350 manual.