I'm not sure if can *do* that and don't ask me if it works or not (but there is no shaming in trying naman :P)
The reason why (if ever there is a chance) I'd rather go to the vehicle factory mismo instead of asking customized options from a dealer is really simple: Sales people can be STUPID.
I don't want ignorant sales people to take my order kasi baka they may do something unintelligent. Halimbawa, if I say to them na I want AFS (para sa stock HID Xenon headlamps) as a feature for my car, baka isipin nila na para aircon iyon kasi baka akala nila: AFS= Automatic Freezing System

If I request for 11 speakers + 11 airbag option (instead of standard 6 speakers + 2 airbags) baka di rin nila isama. If I request for VDIM, baka hindi rin nila alam.
Tapos, kung nagkamali sa specs, it becomes worthless. You'd have to send it back sa planta sa Japan just to add these specs again. That's why it's better to go there in person. Para you can see that the features that you want to put are in there and that you can see the processes as your car is being manufactured.
Also, since there are some parts that may involve requests/advice from the plant's technical staff, it's indeed important for me to be in person. This also avoids any mistakes/errors that can be committed.
Guess that's it.
