its not exactly user friendly is it, and the fact that the diagram labels are in Japanese does not help either.
Someone else might know how to do this better then me but i hope this helps.
search using the "section index" in the NFA010 screen (SEC Index), best way as thats in english, then once you have brought up the NFA025 illustration screen double click on the part listing number (in your case 80682RH & 80682LH) to bring it up in NFA010 screen. once the selected parts are in the NFA010 screen press F5 to list part numbers.
The peice of trim that sits over the tweeters in the doors part #s are
RH is 80682-85F10
LH is 80683-85F10
its simpler if you enter your cars vin number each time as sometimes for things like interior you might get 7 options if you just use the S15 search.
in the NFA010 screen where it says VIN-Code in the first box just put S15 then the one right next to it put the last 6 digits of you VIN number like 006879 or whatever yours is, then click the OK button on the right and wait 5sec, you dont need to enter any other info in the other boxes like model or model series. This way is also helpfull as it shows exactly what your S15's parts were as they left the factory in japan.
Hope that is of some use.